This is all interesting to me. Ive just ordered the AIYIMA 04 with the TI TPA3251 chip. I found it on ebay because I was looking through the Texas Instruments website, trying to find the most recently introduced TI class D with what TI promotes as its Ultra-HD with pure path circuit design. I have had an SMSL AD18 I used for about a year and a half. The SMSL impressed my brother who is a musician (went to the Sydney Conservatorium of Music etc) who concentrates on electric guitar these days. He came over and plugged his guitar into the SMSL and was amazed at the sound, especially the speed of the amp. Zero delay between the time he plucked a string to when it cam out of the speakers. Apparently that's very rare. "It sounds like we are in a studio" He said. Then he asked how much the amp cost and I told him. And he took the Lord's name in vain and said "What the hell? Do you know how much people pay for equipment that can do that ?" I said, being a VW nut, not a musician, "no idea". And he said "Thousands." I said well you cant have heard many modern Class D designs Dave and he said, oh its class D? I said yea, and he said, well mostly young whipper snappers buy those. And so seeing as its his birthday and seeing as he's on the bone of his arse right now, I figured I'd try the Aiyima and send him which ever is worse sounding out for the two for his birthday. Making music involves, it seems, a whole raft of considerations and aims which are different, very different, to the aspirations of people who seriously enjoy listening to music. One thing came out of the measurements (was it in this forum or some other?) of the SMSL AD18 was the nature and extent of the amp's distortion. And that, for the musician who was blown away by the amp, not a consideration to his ears and perception. The thing that astounded him was the timing of the amp. It was fast. He's no slouch and it kept time with him. And it sounded live. Because it, well, was. Normally its a very nice amp for money. When you plugged a guitar into it, it sounded like a thousand bucks worth. Not its purpose in life, but it did sound way bigger than it is. Im hoping the Aiyima in its own way will be as good.