Ordered from Taobao and received the amplifier on Monday after a week. After spending some time with the amplifier, I think I am ready to give a brief impression on it. I used it to drive my HD800, HE1000 and ZMF Vibro II. To me, the IHA-6 drives HD800 and HE1000 well. It is a pity I do not have a decent solid state amplifier to compare with. At the end of the day, I still preferred my DNA Stratus with HD800 and HE1000 as the tube amplifier was able to produce a seductive and liquid mid which I like. However,technically, the 2 amplifiers were pretty close despite the huge difference in price.
On the other hand, I thought the IHA-6 was an excellent match with the ZMF Vibro II. Despite not being the most technical headphone, the Vibro II with the IHA-6 was very engaging, fun and realistic. There is so much synergy that I will actually put the pair on par with my Stratus/HD800 in terms of enjoyment and the IHA-6/Vibro II pair only cost 1/4 of the other pair.
To conclude, the Cayin Iha6 is a very capable amplifier with plenty of connection and power options. The small footprint and price make it a very attractive option in my opinion. It is a keeper for me.