@paulcreed
maybe my use of the word ’zippy’ is getting us hung up a bit... i found the voicing of the rme to be somewhat treble forward and i would not call the midrange or bass warm... neutral and fast i would say, but not bloomy or warm in the least to my ears (there are significantly warmer-voiced dacs - metrums, ayre codex, mhdt’s in stock form, esp. with the we 2c51 tube come to mind)
i currently have a number of mhdt units (orchid, stockholm, istanbul), the stockholm i have is modded with pcm56k chip, vishays diodes and mundorf silver oil caps, other two are stock... i do find the modded stockholm to have the most highlighted treble and the best drive of the 3 mhdts, so i am not surprised your modded mhdt plays slightly brighter than the stock units - of course, the mhdt units’ sound can be further shaped with choice of tube, options are plentiful and the range of ’adjustment’ is fairly substantial
to me, i don’t fault the tonality of the rme... voicing is a matter of taste, and many systems and listeners like more ’effortless’ detail that a forward treble voicing affords -- my personal feeling is that the weakness of the rme is its relatively flat and narrow imaging... tonally i find chord dacs similarly detail oriented but their imaging is vastly superior, wider deeper bigger stage, simply more holographic, leaving aside tonal balance - the mhdt’s really excel at imaging and dimensionality...
this being said, i had the rme for about 6 months (before selling it to a good friend who is a headphone listener, for which i think the unit is really ideal), and i did not use an upgraded ps with it, so maybe i have not heard it at its best -- then again, i was using the chord qutest at the time with its own factory supplied switching ps as well...