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Integrated amplifier



Manufacturer: ARTMAN electronic / Abyssound
Price (when reviewed): 19 000 zł

Contact: ul. Lipowa 3
30-702 Kraków | Polska


Provided for test by: ABYSSOUND

ntegrated super-amplifiers are not a new idea. One of the top models is Soulution 530 priced at 50 000 USD (review HERE). I remember the first one of this kind that was strongly promoted in our country – it was MA 6850 from McIntosh. At the time I worked for Audioholic, then Polish distributor of the brand which gave me an opportunity to meet many people who came to buy this amplifier and to listen to what they had to say about it. It happened more than once that we took this huge box with amp inside and carried it into Fiat 126 that looked like a total wrack about to break down – at the time for what one had to pay for this integrated would have bought him a few such cars. As hard as it is to imagine today back then this model was almost constantly back ordered, we never had enough of them to satisfy the demand.

Most customers when they talked about the amp used whole phrases taken from its reviews. I think they might not even realized that, but at the time it happened a lot. Times changed. Industry changed, matured and so did the customers who have much more experience, who know much better what they want. On the other hand even though generation change does not come very quickly it still does which means that there is a fresh supply of new music and audio aficionados coming every day. They need to learn the 'audio language', learn what some phrases mean, they have to learn how to listen and about what they can actually hear. They get to know different systems, devices, they get to learn that there are different 'tastes' in audio – some are sweet some are sour. These people introduce to audio industry their needs which are often different than the ones we (I mean older ones), they often use different sound sources than we do.

The ASA-1600 might also be called an integrated super-amplifier as the MC 6850 was, because it is also expensive and it was created when designers combined previously existing, much more expensive, preamplifier and power amplifier. Both components had to be scaled down to achieve this price level. But it offers something extra too. I mentioned in my editorial the change that happened in audio in recent years. Huge popularity of computers created a new reality, where music servers and computers are often parts of even high-end audio systems.

Another phenomenon – vinyl raising back from ashes forced many manufacturers to develop also devices used for records playback. Today many system use two sources – an analogue one and a digital one. ASA-1600 designers seem to be fully aware of current market expectations and the functionality of their latest product is the best prove of that. Except for its basic role – amplifying signal, it also offers a high quality phonostage integrated into the amplifier. The rear panel features impedance and gains adjustments, and the preamplifier features a dual-mono design so each channel is placed on a separate board.

Vinyl is a child of the 19th century. On other hand an integrated amplifier featuring an in-build D/A converter is a creation of the 21st century, despite the fact the first such products were released by Technics already in 20th century. But only now, in 21st century a digital input became a fully-fledged one, sometimes even the most important/having bigger value for user one. AbysSound realizing how important D/A Converters are in today's audio, decided to equip ASA-1600 also with a DAC sporting multiple digital inputs, including also an USB one. It is limited though to 24/192 PCM files and it does not accept DSD format.

The amplifier is really well made and its operation is user-friendly. All information useful for user are shown on a display. Menu allows user to set start volume level (for after one turns the device on). Plus there is one more 'trendy' element – a headphone output. Also hear designers did not cut corners and did not use speakers output for it (as many other brands do). What you get is a high quality headphone amplifier with its own volume control software. When you plug headphones in volume level is automatically increased, when you plug them out volume is turned down so you don't have to worry about your speakers being damaged by loud sound.

Owner, designer

There were a few people involved in a process of designing the ASA-1600. All of them had extensive experience with audio technologies. Dr Julian Studnicki designed amplifier's circuits, Łukasz Chmielowski was responsible for mechanical design, software development and he supervised the production of mechanical elements, Michał Maciukiewicz – an industrial designer from Cracow's Art Academy – created a design of a front panel, Piotr Kozioł designed a controlling circuit including display, safety circuits, and PCBs. I was responsible for preamplifier section, DAC, phonostage and headphone amp.

The whole development process of this integrated amplifier took us 2 years. At first we created a design of a chassis and front panel Together with industrial designer, Michał Maciukiewicz we worked for 3 month before we arrived at satisfactory results. After thorough analyses we chose the concept of a front panel combining aluminum with acrylic element. Unlike in case of out other products that all sport anodized aluminum fronts this time we decided to offer our customers a chance to chose almost any color of a front panel

Then we designed an output stage, built a prototype that underwent critical tests, including long listening sessions. After few month of those tests and tuning the original project we developed a new version of it. We re-designed voltage stage and further developed output stage. Just like in our power amps also here for output stage we decided to use BQVA (Bi-Quartet Voltage Amplifier) for voltage stage. The whole development of the power stage for our integrated took more than a year. The power amps work in dual mono configuration. This solution allowed us to eliminate power grid related hum completely. For the output stage we used three pairs of SANKEN: 2SA1295 and 2SC3264 bipolar transistors. A power supply section for each output stage features Nippon Chemi-con capacitors with total capacity of 80 000 µF.

We have been developing our own DAC for 7 years. During this time we created several prototypes based on AKM and Burr Brown (TI) chips. During the process we developed our proprietary solutions for I/U converter, filters and output followers that are based on discrete elements. We were able to used all gained experience when creating a DAC for our integrated. After numerous listening sessions we decided to use the AK4399 chip for this project. The whole circuit between AK4399 and potentiometer in preamplifier section is balanced. The S/PDIF receiver features AK4118 chip and USB input sports CM6631A. It's a USB2.0 true high-speed audio processor that features asynchronous synchronization transfer to reduce clock jitter.

The preamplifier section features solutions sourced from THAT, a company specializing in solutions for pro-audio market. We decided to use latest TI LME49XXX chips. The whole preamplifier section is fully balanced including volume control that sports two MAS6116.

Another attractive module we included in our integrated amplifier is a phonostage. In fact we took the circuits from our flagship phonostage, ASV-1000, and built them into the integrated as two separate, mono modules. The only difference compared to ASV-1000 is a power supply section that had to be scaled down because of limited space available inside integrated.

When designing this amplifier we spent a lot of time when developing a power transformer for this project. Its been custom designed and manufactured upon our specification. It features special electric and magnetic shielding. It is rated at 830 VA. This gives the amplifier a huge headroom and a proper current supply to drive even low impedance speakers.

ABYSSOUND in „High Fidelity”
  • REVIEW: Abyssound ASP-1000 + ASX-2000 – preamplifier + power amplifier, see HERE
  • BEST SOUND 2014: Abyssound ASX-1000 – power amplifier, see HERE
  • REVIEW: Abyssound ASX-1000 – power amplifier, see HERE (Polish)
  • 10/10 CONTEST – RESULTS: Abyssound ASP-2000HF – linestage, see HERE (Polish)
  • 10/10 CONTEST – INTRODUCTION: Abyssound ASP-2000HF – linestage, see HERE (Polish)

  • Recordings used for the test (a selection)

    • Anna Maria Jopek, Barefoot, Universal Music Polska, „Promo Copy”, CD (2002)
    • Charlie Haden & Chris Anderson, None But The Lonely Heart, Naim naimcd022, CD (1997)
    • Cream, Disraeli Gears, Polydor/Universal Music LLC UICY-40023, Platinum SHM-CD (1967/2013)
    • Ed Sheeran, X, Warner Music UK/Warner Music Japan WPCR-15730, CD (2014);
    • Enya, Dark Sky Island. Deluxe Edition, Aigle Music | Warner Music UK/Warner Music Japan WPCR-17045, CD (2015)
    • Marcel Dupré, The Mercury Living Presence Recordings, Mercury Records/Universal Music Company 478 8388, 10 x CD (2015)
    • Miles Davis Quintet, Relaxin’ With The Miles Davis Quintet, Prestige/Universal Music LLC (Japan) UCCO-40005, Platinum SHM-CD, (1958/2013)
    • Mobley/Cohn/Coltrane/Sims, Tenor Conclave, Prestige/Analogue Productions CPRJ 7074 SA, SACD/CD (1957/2014)
    • OMD, English Electric, 100% Records/Sony Music Japan SICP-3810, CD (2013);
    • Pat Metheny Group, Offramp, ECM/Universal Music K.K. UCCU-9543, „Jazz The Best No. 43”, gold-CD (1982/2004)
    Japanese issues available at

    Sound quality offered by solid-state amplifiers improved significantly over the last several years. The first products made in 1970ties and 1980ties even today are considered pure high-end and still sound fantastic. Over time technologies, used elements by also customers' expectations evolved. Designers followed all those changes and as a result also the devices offered different sound. Designers went after better transparency, selectivity of the sound and better bass control. Some of the managed to achieve really interesting sonic results. From today's perspective one can say that not all these changes were actually for better and that there were also some dead ends on the way. Only the last few years seemed to be sort of 'return to the roots', to the best achievements in solid-state technology but utilizing most recent achievements in this field too.

    Listen to ASA-1600 and there is a chance that you will feel like you did when you listened to class A Krell KSA-50 for the first time, or when you were astonished by the performance of Mark Levinson No.33H. I'm not saying that's exactly the same sound. AbysSound has their own concept of the sound. But I'd like to point out a certain sonic feature of this amplifier that is timeless, that appealed to so many audiophiles and music fans when they listened to the best products from 1970ties and 1980ties which now has been combined with a today's understanding of a role of transistors in a power amplifier.

    This amplifier from Cracow at first seems to be quite dark sounding at first. For years it seemed that it was an inherent feature if class A. But later it turned out that it was not about the class A itself but about the way transistors were used. The class A amplifiers made currently by Accuphase and another leading brands sound very differently from those before mentioned ones by Krell and Mark Levinson. They offer open, dynamic, resolving performance.

    Abyssound offers some qualities similar to those of older Class A Sudgen or Musical Fidelity amplifiers, but also some reminding me of the Soulution integrated. This impression of a 'dark' sound comes from a sound that is very rich with harmonics. It's not something one can actually hear. One perceives it as particular richness, fullness and depth of the sound. ASA delivers it all. It presents the better side of most recordings directing listener's attention to timbre, tonality richness and differentiation. This creates a very positive impression, a bind with music one listens to.

    It is a very rhythmic and powerful presentation. It's surely not dull or boring type. I listened to bass guitar from Offramp by Pat Metheny Group, Charlie Haden with Chris Anderson and electronic music from OMD's English Electric. In some way these are combined with a rich ambiance, density of the sound and a slight shift of tonal balance towards lower end. Treble is always proportional with lower part of the range. I never felt as there was missing something in the upper range. High frequencies are rather smooth, silky and not particularly crisp. The sound is energetic, it has a flow that keeps us on our toes as if the amplifier perfectly controlling speakers extended its control over us. It's a quite direct presentation delivered directly from the music medium to our head.

    A description of bass performance would be very similar. I could easily tell that amplifier drove and controlled speakers effortlessly while the biggest Harbeth speakers are not particularly easy to drive. This control manifested itself as a silkiness of the sound a wonderfully conveyed pulse of each recording. Leading edge of the bass guitar seemed slightly softened. But it wasn't caused by lack of energy, or sluggishness of the sound. In fact it was quite the opposite – there was rhythm and density of the sound and no hint of sluggishness But the leading edge was not accentuated.

    It's a similar difference as between how the second Star Wars trilogy (parts I-III) and part VII were filmed. All use a lot of CGI but the older parts do it in more ostentatious way creating a bit exaggerated world. On the other hand in the Force awakens CGI is used but they tried to hide its usage better and it looks more like analogue tapes with parts IV-VI, but to achieve that they used now up-to-date technology.

    As a result Abyssound integrated delivers sound that is different than almost any other one can find on the market. This amazing richness of the sound is not synonymous with palpability. The holographic soundstage is presented behind speakers. Usually such a distant presentation means that sound lacks some energy and some richness. But not in this case. ASA delivers rich sound with a proper bass foundation and yet listener does not feel like sitting face to face with performing musicians but rather further away from them, in some distance. That's exactly why classical music sounded so well, that's why I loved Marcel Dupré's organ from the recently released new remasters series of Mercury Living Presence albums. But that's also why Ed Sheeran on X sounded really good.

    Soundstage is huge, especially its width but also height. The phantom images on this stage are nicely nuanced both tonally and dynamically. Well, in fact this amp does not present phantom images in particularly distinct way, it prefers the bigger picture rather than smaller elements. Separation is not that important in this presentation. Any elements in upper midrange/treble area that is particularly energetic shall be presented as such. But with a bit silky leading edge and dense background.

    All these sound features come together to create a fantastic, so immersive presentation. Obviously there are some elements offered by Abyssound separates, or by differently 'voiced' integrated amps from other brands, that ASA-1600 will not be able to offer. The resolution of this amp is surely above average but its not so well pronounced, one can feel it rather then hear it. Texture of each instruments is 'fused' within its body and the body itself is not that distinctly differentiated from the background. As I already said they create a bigger whole and it's this whole that is differentiated. The background is place closely behind basic sounds and so the acoustics of each sound source is not so precisely conveyed. On the other hand the general acoustics of the recording is conveyed in a very nice fashion.


    All the above were my observations with my Ancient Audio Lektor AIR V-edition CD Player connected via analogue XLR input of the Abyssound. Later I used same Player as a CD Transport delivering signal via coaxial cable to ASA's RCA S/PDIF input. I also used my HP Pavilion dv7 laptop to send signal via USB to the amplifier.

    The DAC in-build in AbysSound offers a very good performance. Deep, well balanced sound with high dynamics. Treble is more accentuated and lower midrange not so rich as when played via analogue input by my CD Player. Bass on the other hand seemed more taut. Sure, the sound is not as refined as with my CD Player but nobody said it would be – DAC is just a complimentary element to the integrated amplifier after all.

    It offers level of performance that surpasses most CD Players from 5-10 thousand PLN price range. Some of them, like Soulnote SA300, offer more refined treble and even smoother overall presentation, and Ayon CD-7s delivers more massive sound with richer lower bass. Anyway owners of this AbysSound should rather consider buying some nice CD Transport. Unless they have more than 10 kPLN to spend – then sure, they could buy some high quality CD or SACD Player. The USB input is quite good too so as long as owner plans to use mostly phono input (as the phonostage is really good!) and either analogue or digital input for a CD Player/Transport it should be fine.

    Both phonostage and DAC modules of this amplifier are really solid performers. I treat them as attractive add-ons to the amp. Headphone amplifier on the other hand is a different story. I tried it out with a few headphones and each time it delivered dense, rich sound. Each time performance was also dynamic, powerful, with a great bass too. Headphone amplifier not only delivered a refined performance but was also able to deliver enough current to drive even such difficult load as HiFiMAN HE-6.

    Only comparison with top headphone amplifiers like Bakoon Products HPA-21, that cost almost as much as the whole ASA-1600, proved that some elements could be delivered in an even better way. Korean amp provided even more resolving sound with even more impressive depth. Also both range extremes, bass and treble, were better extended.

    These elements did not create some huge gap in level of performance between AbysSound and Bakoon but those who search for top quality headphone system would probably decide to buy a separate top notch headphone amplifier. Everybody else will most likely be absolutely satisfied with what ASA-1600's headphone module has to offer.


    This is not the best amplifier in the world, nor the best in price range up to 20 kPLN. As we all know this is a very competitive market segment with such great products like: Concerto elinsAudio, or bit more expensive Hegel H360. On the other hand to get a significantly better performance one would have to acquire something like Accuphase A-470 (Polish) which is also significantly more expensive. So within 20 kPLN price range the individual decision will rather be based on sonic character preferences, aesthetics, and functionality of device that suits particular needs best.

    Let me start with the latter. ASA-1600 not only offers almost everything one might need but each of these additional modules offers a really good performance, in fact good enough for a separate device that could be successful (I am trying to convince manufacturer to give it a try). Both phonostage and DAC could easily compete with other products priced at 3-4 (maybe even more) kPLN range. The headphone amp could cost even more..

    AbysSound amazes with an interesting combination of an „old-fashion charm” with a very modern-like resolution and bass control. Sound might be perceived as bit dark, but it's not warm nor dull. A great bass control combines with its bit 'silky' leading edge. While both range extremes seem slightly rounded there is no obvious emphasis in the midrange. ASA-1600 delivers a relaxed presentation that's never pushed forward towards listener and yet it is rich and dense. Great product.

    ASA-1600 is a stereo integrated amplifier. It's a partially balanced design as the Class A preamplifier section is balanced and the power amp isn't. Right after signal passes through RA inputs it is symmetrized and only then processed. Apart from linear inputs amplifier features also a phonostage input with adjustable gain and impedance (adjustable via DIP switches), D/A Converter with few digital inputs including USB, and a headphone amplifier. Digital inputs accept PCM signal up to 24 bits and 192 kHz. One doesn't really need even higher resolutions, although DSD capability would be appreciated.

    Its a mighty, heavy device, a very solid too – it looks like it could survive a crazy rock concert or a house party. It surely doesn't look like a typical fragile 'audiophile' product.


    Front is made of aluminum finished with a special paint, with an acrylic plate mounted in the center. On its left side there is a „standby” with a green circle around it. Below there is a 6,3mm headphone output that delivers signal from a full fledged headphone amplifier module. After a jack is plugged in volume level automatically increases, when it's taken out volume also comes down. It's a safety measure protecting loudspeakers from a sudden volume level spike that could lead to some damage.

    On the right there is a volume control knob that sports quite unusual shape. After amplifier is switched on a nice red logo and a green dot-matrix type display, both placed under acrylic plate, lit up. Display delivers data on volume level and selected input. After any change to these values for a few seconds information is displayed in enlarged form. User can adjust display's brightness in few steps but can not turn it off completely.

    Near the lower edge there are four push buttons – two allow input selection, the other two allow to chose commands in device's menu. User might chose the maximum volume level (as a protection against children playing with it), and the start volume level (the one amplifier uses after it is turned on).


    Rear panel sports a bunch of connectors. A digital section sits in upper part and it features: coaxial, optical TOSLink, BNC, AES/EBU and USB. Next sits phonostage module with solid input sockets and DIP switches for gain and impedance adjustment. There is also a ground switch and IEC socket with on/off switch.

    Below there is an analogue section. Input 1 seems to be taken a special care of as it features rhodium plated RCA connectors and also balanced XLR sockets. Other 5 RCA connectors are much simpler ones of somewhat lesser quality. Speaker posts are again of high quality with rhodium-plated contacts. These reminded me of Furutech products but in fact they are custom made by a Taiwanese company.


    The electronic circuits spread over few PCBs. At both sides there are large radiators with three pairs of bipolar Sanken (2SA1295 + 2SC3264) transistors working in each channel. They are arranged this way not to increase output power but to improve damping factor – Japanese Accuphase does it also same way. The circuit seems quite complex and it sports high quality passive elements like, for example, polypropylene Wima capacitors. Signal to speaker posts is delivered using thick copper cables. This board features also 4 large Nippon Chemi-Con filtering capacitors per channel.

    Preamplifier section sits on a separate board that also uses high quality passive elements. Preamp utilizes TI LME49XXX chips. The whole preamplifier section is a balanced design including volume control that utilizes two MAS6116 chips. Above sits another board with D/A Converter module. Digital inputs sport coupling transformers that adjust input impedance. Manufacturer decided to use Japanese AK4399 chips made by Asahi Kasei Microdevices Corporation. This whole circuit between AK4399 and volume control has a balanced design. AK4118 works as S/PDIF receiver, USB input uses Cmedia CM6631A chip. The whole USB section sits on a smaller board placed below. Signal travels from USB input into this board with a short USB cable.

    Next to it one finds two vertically placed boards with phonostage modules – a separate one for each channel. Gain stage is based on Burr Brown OPA134 chips. RIAA circuit uses high quality capacitors. Each channel uses separate power supply. Output stage uses separate secondary windings of a huge power transformer.

    A huge power transformer rated at 800W is carefully shielded with thick metal sheet. Above sits AC filter and a standby mode power supply. Another board mounted close to the front panel hosts controlling circuits and display – the latter is galvanically separated from the gain stage. Great, solid design!


    The remote control delivered with amplifier does the job although it would be difficult to claim that it looks good – it's made of plastic and not particularly handy. It allows user to control volume setting, select input (directly or by toggling between them), dim the display, change settings in menu, and switch the amp to standby mode. According to manufacturer in the near future it will be replaced with a new remote with aluminum body.

    Specifications (according to manufacturer)

    Output power: 165 W/8 Ω | 275 W/4 Ω
    Volume control range: MUTE, -111 dB ÷ +15 dB, in 0,5 dB increments
    Frequency range: 5 Hz ÷ 138 kHz (-3 dB, 1 W)
    SNR: > 110 dB
    THD: 0,0045%
    Input impedance (RCA | XLR):
    30 kΩ | 50 kΩ
    Input impedance (phono input MM/MC):
    20 Ω/50 Ω/100 Ω/220 Ω/470 Ω/1000 Ω/47000 Ω
    Input capacity (phono input MM/MC): 47 pF
    Input sensitivity MM/MC:
    0,5 mV/1,5 mV/2,5 mV/5 mV
    Digital inputs: 5 (coaxial / optical / AES/EBU / USB) / DAC 24bit/192k
    Power consumption:
    - normal operation: min 80 W (max 830 W)
    - standby: <3 W
    Dimensions (W x H x D.): 440 x 150 x 450 mm
    Weight: 21,5 kg



    - Turntable: AVID HIFI Acutus SP [Custom Version]
    - Cartridges: Miyajima Laboratory KANSUI, review HERE | Miyajima Laboratory SHILABE, review HERE | Miyajima Laboratory ZERO (mono) | Denon DL-103SA, review HERE
    - Phono stage: RCM Audio Sensor Prelude IC, review HERE

    - Compact Disc Player: Ancient Audio AIR V-edition, review HERE
    - Multiformat Player: Cambridge Audio Azur 752BD
    - Line Preamplifier: Polaris III [Custom Version] + AC Regenerator, regular version review (in Polish) HERE
    - Power amplifier: Soulution 710
    - Integrated Amplifier: Leben CS300XS Custom Version, review HERE

    - Stand mount Loudspeakers: Harbeth M40.1 Domestic, review HERE
    - Stands for Harbeths: Acoustic Revive Custom Series Loudspeaker Stands
    - Real-Sound Processor: SPEC RSP-101/GL
    - Integrated Amplifier/Headphone amplifier: Leben CS300XS Custom Version, review HERE
    - Headphones: HIFIMAN HE-6, review HERE | HIFIMAN HE-500, review HERE | HIFIMAN HE-300, review HERE | Sennheiser HD800 | AKG K701, review (in Polish) HERE | Ultrasone PROLine 2500, Beyerdynamic DT-990 Pro, version 600 - reviews (in Polish): HERE, HERE, HERE
    - Headphone Stands: Klutz Design CanCans (x 3), review (in Polish) HERE
    - Headphone Cables: Entreq Konstantin 2010/Sennheiser HD800/HIFIMAN HE-500, review HERE

    - Portable Player: HIFIMAN HM-801
    - USB Cables: Acoustic Revive USB-1.0SP (1 m) | Acoustic Revive USB-5.0PL (5 m), review HERE
    - LAN Cables: Acoustic Revive LAN-1.0 PA (kable ) | RLI-1 (filtry), review HERE
    - Router: Liksys WAG320N
    - NAS: Synology DS410j/8 TB
    System I
    - Interconnects: Acrolink Mexcel 7N-DA6300, review HERE | preamplifier-power amplifier: Acrolink 8N-A2080III Evo, review HERE
    - Loudspeaker Cables: Tara Labs Omega Onyx, review (in Polish) HERE
    System II
    - Interconnects: Acoustic Revive RCA-1.0PA | XLR-1.0PA II
    - Loudspeaker Cables: Acoustic Revive SPC-PA

    System I
    - Power Cables: Acrolink Mexcel 7N-PC9300, all system, review HERE
    - Power Distributor: Acoustic Revive RTP-4eu Ultimate, review HERE
    - Power Line: fuse &#8211; power cable Oyaide Tunami Nigo (6m) &#8211; wall sockets 3 x Furutech FT-SWS (R)
    System II
    - Power Cables: Harmonix X-DC350M2R Improved-Version, review (in Polish) HERE | Oyaide GPX-R (x 4 ), review HERE
    - Power Distributor: Oyaide MTS-4e, review HERE
    - Stolik: SolidBase IV Custom, read HERE/all system
    - Anti-vibration Platforms: Acoustic Revive RAF-48H, review HERE/digital sources | Pro Audio Bono [Custom Version]/headphone amplifier/integrated amplifier, review HERE | Acoustic Revive RST-38H/loudspeakers under review/stands for loudspeakers under review
    - Anti-vibration Feets: Franc Audio Accessories Ceramic Disc/ CD Player/Ayon Polaris II Power Supply /products under review, review HERE | Finite Elemente CeraPuc/ products under review, review HERE | Audio Replas OPT-30HG-SC/PL HR Quartz, review HERE
    - Anti-vibration accsories: Audio Replas CNS-7000SZ/power cable, review HERE
    - Quartz Isolators: Acoustic Revive RIQ-5010/CP-4

    - FM Radio: Tivoli Audio Model One