I had an ARC LS5 which I traded for a 30SE after hearing the 31SE at HiFiSound in Mpls. The 30SE to 31SE upgrade was very affordable and I was convinced I would do this upgrade. But I wanted to give the MP3 a shot before I sent my 30SE for the upgrade. As I think more, this was closer to 5 or so years ago. I was thinking it was only a couple years but time flies when you're having fun. 8-)
I went to Audio Perfection to borrow the MP3 demo unit. It was fair to assume it was in good working order, all original tubes, etc.,.....at least I would think so if a dealer is using this to sell such a product. I was not able to hear it there that day but they let me play for the weekend.
I took the MP3 to HiFiSound where Bill (salesman) hooked it up in the very back room with B&W N802 speakers. The amps were Classe mono blocks. As much as Bill and I had such high expectations on the MP3 from all the praise on the Atma amps, to say that we were both disappointed on the MP3's performance would be an understatement. I remember the look we both had when the bottom and top octaves were gone ..... not lacking .... but GONE. A return to the 31SE and we could again here the string bass player going up and down the register. And there was so much detail, decays and ambiance with the 31SE. Music was Miles Davis, "Kind of Blue". Even the ARC LS5 that I had taken there a week before was not so severely destroyed by the 31SE as was the MP3.
Almost forgot - I was able to borrow the 31SE and take it home to compare to the MP3 and my 30SE .... and the results were the same. Ultimately, the MP3 was not my cup of tea.
I have since moved onto the Aesthetix Io and Callisto, and am waiting for the Michael Elliot WV preamp. Perhaps one of these days I will try out the MP1.
John