This week we reviewed the Cayin CS-55A KT88, a tube amplifier priced at €1790 featuring analog inputs as well as a digital USB input for audio streaming up to 32-bit / 384kHz from a computer. Does this new generation of tube amps designed to combine analog components with digital technology deliver? Does the use of tubes bring warmth and life to digitally streamed music? Here are a few answers to these questions.
Cayin CS-55A KT88: the brand
For the past 25 years, the Chinese manufacturer Cayin has been specializing in high-fidelity tube electronics: amplifiers, preamps, CD/SACD players, headphone amplifiers, and even recently released an audiophile DAP, the Cayin N8, which we had the pleasure to review. The brand’s philosophy and its scientific approach to sound restitution ensure that each Cayin product delivers a warm and harmonious sound, inherited from the legendary tube amps of the 70s and 80s. The Cayin CS-55A KT88 is no exception and is fitted with high-end tubes and components, not to mention its more than fair price.
Cayin CS-55A KT88: design
What sets the Cayin CS-55 KT88 apart other tube amplifiers is its integrated USB DAC. The latter is capable of handling HD audio files up to 32-bit and 384 kHz from a Mac or PC. The Cayin CS-55A KT88 is a beautifully made tube amp. Its front panel features an on/off switch, a volume knob, a source selector, and a headphone output. The back of the amplifier features two RCA line inputs, a mobile magnet (MM) compatible phono input, and a USB input.
The Cayin CS-55A KT88 is a testimony to the Chinese brand’s know-how. It is fitted with three bulky transformers (one input transformer and two output transformers), and a total of 8 high-quality tubes. The output stage features four KT88 or EL34 power tubes, depending on the model. They are combined with two 12AU7 and two 12AX7 preamp tubes which are used to drive the power tubes. The Cayin CS-55A KT is rated at 2×22 Watts into 8 Ohms and 2×40 Watts in ultra-linear mode. The frequency response ranges from 5Hz to 44kHz, which is more than necessary to get the most out of high resolution digital tracks.
Cayin CS-55A KT88: triode mode and ultra-linear mode
The Cayin CS-55A KT88 can easily go from triode mode to ultra-linear mode; the difference between these two modes is the number of electrodes used by the tube. It is important to note that the KT88 tubes are tetrodes and are this fitted with 4 electrodes which are essential to delivering power. When using a tetrode in ultra-linear mode, the tube is working at almost full power. By using the remote control to shunt one of the elements, the amplifier can be switched to triode mode, which means only 3 electrodes are used. The downside is that in doing this, the amplifier doesn’t deliver as much power. On the other hand, because less electrical components are part of the chain, the sound is more transparent, the lows are more nuanced, the stereo image is deeper and more open, and the high frequency range sounds more natural. The bandwidth is larger, there are more pair harmonics, and the damping factor is reduced. The result is a more pleasant listening experience, as long as the loudspeakers have a high enough sensitivity rating to work with a lower amplification power.
Cayin CS-55A KT88: unboxing
The Cayin CS-44A KT88 tube amp comes with a pair of white gloves which should be used to carefully handle the tubes, a CD to install the DAC’s driver on a computer without an Internet connection, a power cable, a high-end USB cable, and a remote control. We were a little bit disappointed by the remote control which didn’t feel on par with the quality of the amplifier despite its aluminum housing. The buttons on the remote feel loose and are a bit noisy. It is necessary to use a screwdriver to insert the batteries (2 AAA batteries) into a removable plastic compartment. Nevertheless, the remote control is still a convenient way to adjust the sound volume and select the amp’s mode (triode or ultralinear) without having to get up.
The amp is easy to set up once the polystyrene protections around the tubes have been removed. The version that we tested is fitted with KT88 power tubes. The amp comes with the tubes already installed, and all we had to do was to connect the amp to a power outlet and to a source and we were ready to start listening to music. After a short warm up period, that is. Like all tube electronics, the amp needs 10 to 20 minutes to warm up before you may start using it. This warm up period is a way to optimize the tubes’ lifespan and ensure maximal musicality. Once the amp is hot enough to heat up the room, it’s time to start the listening session.
Cayin CS-55A KT88: listening impressions
For our test of the Cayin CS-55A KT88, we first listened to the amp with the Focal Stellia headphones. Using a Mac computer in USB DAC mode (Spotify 320 kbps, and 24/96 as well as 24/192 HD FLAC files) as a source, the amp instantly grabbed our attention with its perfect tonal balance and its dynamic delivery. There is no emphasis on the high or on the lows. With Stan Getz’s Corcovado, the saxophone notes were extremely clear, and the vocals sounded soft and melodious. The most subtle details are restituted, the various tones are pitch-perfect and the dynamics are even throughout the whole sound spectrum. The Cayin CS-55A KT88’s ability to reproduce music in a soft yet dynamic way instantly enthralls the listener. The listening experience oozes with serenity, and we felt compelled to turn the volume up and to keep listening to track after track. Even after several hours, we did not feel any audio fatigue and the listening experience felt increasingly pleasant.
The Cayin CS-55A KT88’s ability to reproduce music in a soft yet dynamic way instantly grabs the listener’s attention.
We then connected the Cayin CS-55A KT88 to the Elipson Facet 8B speakers using Viard Audio Silver HD12 HP speaker cable. Our source was the Elac Miracord 90 turntable directly connected to the Cayin’s phono preamp. We listened to the LP of Serge Gainsbourg Aux Armes Et Caetera and the result was spectacular and extremely refined. This record is often praised for the quality of its stereo separation, and listening to it through the Cayin CS-55A KT88 amp, we understand why. The sound stage is spacious, and various instruments are meticulously layered. The vocals sound natural and are perfectly highlighted. There is no exuberance in the high frequency range, and the lows are deep and pleasant.
The sound stage is spacious, and various instruments are meticulously layered.
We also connected the Cayin CS-55A KT88 in ultra-linear mode to the Davis Acoustics Courbet n°3 compact speakers, also hooked up to the amp with Viard Audio Silver HD12 HP speaker cable. We also used the Elac Miracord 90 and Serge Gainsbourg’s Aux Armes Et Caetera as a source. The soundstage immediately became more authoritative, the highs were more open, and the low-mids were more expertly integrated. The overall restitution was a bit shyer in the lows, and the vocals weren’t as warm and soft as they were in triode mode.
We then paired the Cayin CS-55A KT88 with the Klipsch RP-8000F floor-standing speakers. Like all the other speakers designed by the American brand, the RP-8000F boasts a high sensitivity rating, which makes it the perfect partner the Cayin amplifier. This time around, we used the D-Stream WR100-D network player to stream music from Spotify Connect. In ultra-linear mode, the softness and the balance of the sound stage are as close to perfection as could be. The instruments’ tone is spot on, the vocals are clear and natural. While we detected a pinch of coldness with the Klipsch RP-8000F’s when these speakers were driven by a solid state amplifier, this issue is a thing of the past with the Cayin amp. This is a subtle and warm pairing which completely wowed us.
In ultra-linear mode, the softness and the balance of the sound stage are as close to perfection as could be. The instruments’ tone is spot on, the vocals are clear and natural.
Lastly, Michel, sales assistant at the Son-Vidéo.com store located in Lyon, tested the Cayin CS-55A with EL34 tubes for the output stage. His listening impressions are as follows: “The Cayin CS-55 EL34 integrated amplifier is part of the entry level range of the Chinese manufacturer’s catalog and features 2 line inputs, a MM phono stage, an integrated DAC (32-bit / 384kHz) with a USB type-B input and a 6.35mm headphone output on the front panel. With its EL34 tubes and its push-pull circuit, the Cayin amp is rated at 2×38 Watts in ultra-linear mode and 20 Watts in pseudo-triode mode (which may be activated via the remote control), which makes it a rather well-rounded model capable of driving a wide array of speakers. We tested the Cayin CS-55 EL34 with the Dali Opticon 6, Dali Rubicon 6, Klipsch Heresy 3, Focal Aria 926, PMC Twenty5 23 and Elipson Prestige Facet 24F speakers connected with Viard Audio HP HD 12 and Atlas Equator 2.0 speaker wire. We listened to music streamed from Qobuz Sublime + via the Atoll ST200 Signature et Yamaha WXC-50 streamers. The latter was connected to the Chord QuTest DAC using an Audioquest Forest Digital Coax cable. The Chord QuTest was connected to the Cayin amp using Viard audio premium HD RCA cables.
Pour terminer, Michel, conseiller-vendeur à la boutique Son-Vidéo.com de Lyon a testé le Cayin CS-55A avec des tubes EL34 pour l’étage de sortie. Voici ses impressions d’écoute : “L’intégré Cayin CS-55 EL34 propose, tout en faisant partie du début de gamme de la marque chinoise, 2 entrées ligne, un étage phono MM, un DAC (32 bits/384 khz) avec entrée USB-B et une sortie pour casque 6,35 mm en façade. Pourvu de son amplification en push-pull d’EL34 de 2×38 watts en mode ultra-linéaire ou de 20 watts en mode pseudo-triode (accessibles par la télécommande) cela en fait un appareil assez complet, pouvant favorablement alimenter un large panel d’enceintes. Nous avons testé le Cayin CS-55 EL34 sur les enceintes Dali Opticon 6, Dali Rubicon 6, Klipsch Heresy 3, Focal Aria 926, PMC Twenty5 23 et Elipson Prestige Facet 24F reliées avec les câbles Viard Audio HP HD 12 et Atlas Equator 2.0. La source utilisée était Qobuz sublime + sur les lecteurs réseaux Atoll ST200 Signature et Yamaha WXC-50. Ce dernier était relié par un câble coaxial Audioquest Forest Digital Coax au DAC Chord QuTest lui-même relié au Cayin avec les câbles Viard audio premium HD RCA.”
When listening to the Cayin CS-55 EL34, one can hear all the advantages inherent to tube amplification: spacious stereo imaging, convincing tonal balance, and proper sound transparency. In short, this is a natural sounding and melodious amplifier. All the frequency ranges are handled with both authority and subtlety, as long as the speakers have a higher sensitivity rating and a fairly simple crossover filter, which isn’t always a sign of outstanding quality. We listened to this integrated amplifier with multiple high sensitivity, as well as average sensitivity, loudspeakers, and were never disappointed. The pseudo-triode mode works wonders with music played in halls and large venues (concerts, baroque music, etc…) and obviously with vocals. The ultra-linear mode, on the other hand, is to be used with more “elevated” tracks. We cannot recommend the Cayin CS-55A EL34 strongly enough, and this amp is one of the best selling products in our store. The KT88 version will provide the same listening enjoyment but with a different balance. The KT88 version has more authoritative lows but offers less subtlety and transparency in the mid and high frequency range. It’s all a matter of taste and pairing…
Cayin CS-55A KT88: compared to…
Cayin CS-55A EL34: the EL34 version of this Cayin amplifier is slightly warmer, especially with vocals, but has a less extensive response in the lows as a result.
Taga Harmony TTA-500: the Taga Harmony is a very good amplifier, but it is less powerful and does not offer the dynamic range of the Cayin CS-55A KT88, which is also a lot smoother.
McIntosh MA252: the MA252 does not compete in the same category and isn’t fitted with a DAC, but its sound signature isn’t that different from the Cayin CS-55A KT88.
Cayin CS-55A KT88: conclusion
With the Cayin CS-55A KT8, the brand has managed to combine the unique sound signature of tube amplifiers with the high quality of digital music. Regardless of the source, the Cayin CS-55A KT88 ensures a particularly warm listening experience worthy of a tube amplifier, with great musicality and an extremely faithful delivery. Ideally, it should be paired with loudspeakers boasting a high sensitivity rating and featuring a crossover filter that isn’t overly complex. Without a doubt, this amplifier will be our reference model for driving high efficiency speakers in the future.
What we liked:
- The warmth of the tubes
- The tonal accuracy
- The output power
- The quality of the DAC
- The exemplary musicality
- The amp’s really neat design and vintage flair
We would have like:
- More analog inputs
- A better remote control