I have auditioned the HCA-2 in my stereo system for about three weeks. It is a very fine amplifier for its price range. The midrange frequencies were quite natural and the bass was alright though it rolled off at the very bottom. I noticed that the each high frequency note of female singers alla Diana Krall sounded like it was made of many little pieces. It did not sound smooth like you would expect from an exceptionally good amp. This is characteristic of many but not all digital amps. After sending back this amp, I ordered an Ear-2 from Accoustic Reality in Denmark(AV-Reality.com). After setting this amp up in my system, even straight out of the box, I knew this amp was a definite keeper. I would the describe the sound of this amp as very natural and realistic, dynamic with a very tight and fast bass all coming from a dead quiet background. The high frequencies are smooth and natural. This amp has no dryness commonly associated with digital amps. I would say that this is a true reference amp that cannot be compared to the HCA-2 or any other amp digital or otherwise.