One week in on the Dexa discrete op amps and Tesla tube combo, about 30 hours or so. Voices are very crisp and up front, but with dimension. Studio recordings are a lot more accurate, with depth and harmony to singers. Had Garth Brooks on for a bit, in some recordings you can really tell the studio had an echo to it. The bass is much, (almost too much for my taste), tighter, boom is non existant, replaced with a very accurate thump from kick drums. There is a passage in a KISS song where Simmons is picking a Punisher bass solo. Good grief, I was blown away by the accuracy of the growl that guy can produce. I left the highs alone, slightly pulled back as usual, done since the Ti Crites tweeter domes were installed.
All in all, every statement about the MavAudio DAC, and Tesla tube has been spot on. IMO, (yep, it dont mean a thing), if you like rock, if you like fusion, if you like modern country, buy the MavAudio with the upgraded op amps and GE tube, hook it up, and likely be very happy for a long time.
If you dig jazz, if you want accurate studio reproductions, piano (Diana Krall anyone?), voices, (Eva Cassidy, yes even Leonard Cohen), then do the full monty of Tesla tube and discrete op amp of your choice, and again, be happy.
I got the Dexa's because of price, all three were 120 from a half price sale. Sparko's get their own rave here, don't forget to look into Orange, Burson, or one of the other 2 or three or dozen that are out there.
I agree that the less than 500 in the ModMav is a worthwhile investment, and it punches above it's weight class.