I've now had a chance to listen to the SA-31, albeit briefly.
First impressions were not great. The amp arrived on time and in good condition, but some of the fit and finish reminded me of British "cottage industry" hi-fi of the 80s (think Myst, early Exposure etc.). The enclosure Itself is solid and undamaged, and is clearly made from high-grade aluminum. Many of the screws, however, are not countersunk. The remote appears to be milled from a solid aluminum billet (good
), but the battery compartment cover is a thin sliver of aluminum which bows out in the middle, and the screws attaching it stand proud, to scratch whatever surface it is resting on (bad
). Also, the backplane has clearly been lifted from an NFB-6 (some of the RCA sockets are labelled "XLR" and "ACSS"). Model name and serial number are handwritten on sticky labels.
I don't want to belittle Kingwa's achievement - this is a low-volume, specialist product built by a small company, and the bulk of the money has been spent where it matters: on the inside! It's just that we have been spoilt by the quality of companies such as Opera Consonance or Matrix' casework.
Now to the important bit: the sound. I tried it with the HE-500 and HD600. Interestingly, the 300 Ohm Sennheisers need about as much power to drive them as the HE-500s (unlike the transformer-coupled tube amp I am used to). All listening was carried out on the low gain setting, and never above a volume setting of 30. The source was the Opera Consonance CD2.3, an upsampling CD player with a tube output stage producing about 2.3V.
Initial impressions were of a warm, lazy sound with little midrange detail or transparency. The HD600s were soporific, the planars just so-so. I couldn't believe that this was all the amp was capable of, so I left it running for about 3 hours on the HE-500s, and came back later. I presume this must have something to do with the capacitors needing to form, as the sound was transformed. Still not perfect, but much clearer and more transparent. Where it improves on the Cyber 20 is in the area of soundstage width (enormous) and bass extension (seemingly bottomless). Dynamics are also a major improvement over the tube amp! Where it still loses out to the Cyber 20 is in absolute midrange transparency and image depth. The SA-31 is "CinemaScope" rather than holographic.
I tried the HD600s again early this morning, before leaving for the office - still very veiled, but an absolutely black background. I have yet to try the Audio Technicas.
On balance, then, an interesting niche product with considerable potential. I do feel that it is perhaps better suited to low impedance cans (especially orthos), and that it will need MUCH more burning-in.
Am I correct in assuming that it is factory set to the least warm setting? I haven't opened it up....
When it has perhaps 100 or so hours on the clock, I will publish a full review. This amp promises to be something of a big block V8 for your ears...