[Edit 2006.06.21] In 2006 Cayin HA-1A is now advertised by Acoustic Sounds in the US, and Stereophile gave it a glowing review in June, 2006. After discussing with other head-fi owners of this amp and some more experimentation, I have decided revise my review quite a bit. Here is a side view with the black casing removed. Here is a another side view with the black casing removed. Introduction: Cayin HA-1A is a headphone amplifier that could catch many head-fiers’ attention at first sight. Its appearance is classy, and its internal circuitry is neat. It uses single-ended tube circuitry with an output transformer linked to a four-way impedance selector. It can additionally act as a tube preamplifier and a flea-power SET amplifier for speakers. Since it is designed and manufactured by a Chinese company, it is priced quite competitively in some markets. The only question is: how does it sound? Background: Spark Audio used to be a subsidiary electronics department of Chinese Air Force. Its association with tube electronics without doubt dates back to the old days when Russian aviation technology heavily employed vacuum tubes. After its privatization, Spark audio decided to apply its technical expertise into consumer audio, and has become one of the most reputable audio companies in China. It designs and markets its own products under the Spark brand in China and the Cayin brand in some foreign markets. As of summer 2006, Cayin HA-1A is now actively advertised by Acoustic Sounds in the US, retailing for $750. Its price seems to vary widely in different markets. In China it appears to be slightly under $300 USD (220V version), but it is said that export units of Chinese audio electronics have better components and quality control. German version (220V) appears to be extravagantly priced at over 800 euros, maybe it is maxed out or something. 110V version in Japanese websites is around $600, and on Taiwanese website for $400 (now discontinued). I acquired mine used from head-fier Archosman, who got it from The Tuner Guy in the US back in 2004. Features: As can be seen in the pictures, the front plate design is nothing short of excellent. The observation window is the coolest feature and provides a beautiful of the tubes. Here I won’t delve into the little tricks that Cayin implemented to make the tubes look more sexy than usual. The internal circuit is very neatly laid out and the soldering job looks very good, a notch above two other Chinese manufactured amps I have. It uses 12AX7*1, 12AU7*1 and EL84*2. The output tube can be wired in ultra-linear or triode mode, which can be selected by a switch in the back. In the back there is a four-way impedance selector to choose the suitable output transformer configuration for headphones with 32-600 ohms impedance. It can output ~1.5 W at any of the four settings and hence is an extremely powerful headphone amplifier. It can easily drive K1000, which requires at least 400 mW into 120 ohms. There is one set of speaker binding posts in the back for 8 ohms speakers, and I normally attach 62 ohms resistors to them so the tube always see a load when I unplug the headphone—very handy indeed. The speaker output is automatically disabled when the headphone is plugged in. HA-1A can also act as a pre-amp providing 14 dB of gain. There is a switch in the front to activate pre-amp out, which automatically disables headphone and speaker outputs. In the back there is only one set of RCA input and one set of RCA output. Sound Quality: In a nutshell, Cayin HA-1A has an open, pure SET sound worthy of its asking price although attention must be paid to selecting low-noise tubes if one uses high-sensitivity headphones. I normally listen to Cayin in triode mode instead of ultralinear. Triode mode sound a bit smoother and purer, while ultralinear is slightly more dynamic and bassy. The difference is noticeable but subtle. At home, I could only compare HA-1A to Benchmark DAC1’s internal amp. Driving AKG K501, Cayin is smoother and warmer. The midrange purity of K501 is enhanced while the treble sibilance is removed. The massive power of HA-1A also brings out more bass from K501, even at normal volumes, a phenomenon familiar to many K501 owners. I also compared the built-in headphone amp of my PreSonus Station. PreSonus also produce good bass and soundstage with K501, and has a plesant, relaxed sound. But PreSonus' SS amp does not have the tonal sweetness of single-ended tube circuit. Simply put, Cayin has the SET tonal purity that is highly sought after by audio pusrists. On the other hand, Grado SR225 reveals Cayin’s potential limitation. Since SR225 is quite sensitive, Cayin’s self-noise becomes noticeable. The level of self-noise is highly dependent on the tubes used, especially 12AX7. With the tubes I have, I could reduce this noise to a low-level hiss similar to analog tape hiss heard on CDs. Once music starts playing, it becomes basically inaudible, and does not mask the low-level details such as the maraca sound in Rebecca Pidgeon's "Spanish Harlem," featured on Chesky's "Ultimate Demo" disc. When no music is playing, I can barely hear any noise on K501 and absolutely pitch black on K1000. There is nothing wrong with HA-1A's design or implementation. It's voltgae gain is quite high so it can drive even the monstrous K1000, but the tube's self noise is also amplified. It is therefore important to shop for low-noise tubes if HA-1A is to be used for low-impedance cans. Initially, I did not like the sound of Cayin HA-1A with SR225. When Benchmark drives SR225, it has killer speed and in-your-face presentation that make rock music very exciting. HA-1A makes the sound more mellow and spacious, which seemed boring for metal, but now I really like it for the more mellow kinds of pop music like Beatles and what not. At the 2005 So-Cal meet HA-1A was compared against a Single Power PPX3 and an RSA Raptor. While driving HD650, another head-fier and I were surprised at how different the two sounded. PPX3 sounds darker, warmer but also less clear, slower and less resolving. PPX3 is slightly too “tubey,” IMHO, and HA-1A is more accurate and neutral. When HA-1A was being compared against the Raptor, we had Ray’s headphone switch box to do instant A/B. Several of us who participated all thought the difference was extremely minute. There is basically no difference in terms of imaing, tonal quality and dynamics. To my ears, Raptor sounded slightly more detailed and that’s about it. We used both K1000 and HD650 for comparisons. Raptor has somewhat lower noise so it is still a bit ahead, but Cayin sounds so similar to Raptor that it is almost surprising. Also at So-Cal meet, Cayin HA-1A received some very positive comments from other head-fiers (at the meet the tubes I used caused quite a bit of hiss). One noted that HA-1A drove K1000 better than the single-ended tube amp he heard at Detroit meet. Another head-fier virtually tried every amp at the meet and thought HA-1A matched his HD590 the best for his favorite rock CDs. I tried quite a few expensive cans with HA-1A and most of them sounded pretty good. More recently I also compared HA-1A with Rudisptor RP33, and thought they are different but equal. Both had smooth treble but one is tonally pure SET smoothness and another is the resolving but tamed SS smoothness. Rudistor has a lower noise floor but Cayin has higher output power. In my system HA-1A’s main task is driving K1000. In triode mode, HA-1A’s warm and smooth sound cures K1000’s brightness. The midrange purity afforded by this combo leaves little to be desired, and the top end remains open and airy—an AKG specialty. For a livelier listening where more treble energy and bass is required, for instance some jazz recordings, I would occasionally switch to ultralinear mode to spice things up a little. HA-1A can drive K1000 better than any amp I previously tried in this four amp shootout. In summary, HA-1A’s sound quality is worth $750 price tag when compared alongside other reputable tube amps. For a tube amp, its sound is the clear and airy type, not overly warm. It is especially suited for high-impedance, low-sensitivity cans because of its massive power capability. In my experience there is not a single power-hungry headphone it cannot conquer with authority. For low high-sensitivity cans low-noise tubes have to be selected to minimize self-noise. Additional Features: As a pre-amp HA-1A worked pretty well when connected to the Sonic Imapact T-amp (volume switch maxed out) to drive speakers. Noise is not a problem, and it does add some nice warmth to T-amp. As a speaker amp it can deliver 2.2 W into 8 ohms in ultralinear mode and 1.4 W into triode mode. Unless one has super sensitive speakers, it cannot be used in a full-size speaker system. However it is still possible to use HA-1A to drive ordinary speakers for a desktop system in a small office or study room, where it doubles as a headphone amp. Plugging the headphone jack automatically mutes the speaker, which is a useful feature in such environment. Within the first watt or two, HA-1A can deliver a detailed, smooth sound with lots of airiness and ambience. In other words, it delivers SET goodies not just into headphones but speakers as well. Within the first watt, I would rate it over the four integrated amps I have recently compared in a shootout, some of which costing nearly $1000. Conclusion: Cayin HA-1A is definitely an eye-catcher, and its sonic performance is as good as its looks. It can sound as good as other headphone amps I have heard below $1000 USD, delivering an open, smooth sound with the tonal purity one would expect from SET topology. It can drive any low sensitivity headphone with ease, but using it with high sensitivity headphones would require some attention to choosing low-noise tubes. In addition, it can perform satisfactorily as a pre-amp or a flea-power SET speaker am, which makes it a really great bargain. Its small foot-print and enclosed tube design makes it placement friendly at home or in the office. When Stereophile reviewed this amp, Sam Tellig says it is as good as headphone amp can get. I don't agree with Sam on this one but I believe HA-1A's performance is good enough to match other headphone amps in its price range. It is the Cayin HA1A's additional features that make it stand out as a good bargain.