Thanks for your point of view. I aggree M1 is old fashion, and M-DAC a little fuzzy but quite musical though missing fundamentals.
I understand you assimilate Accuracy with a strong presence of trebles.
As I mentionned, IMO Space and Accuracy is for me more a question of dynamic and phase.
When the treble of the string arrives exactly at the same moment as the fundamentals, with a lot of impact and density.
At this moment the space is respected and you get a lot of depth.
This depth is mostly missing with the SU8.
Audition of a good symphonic recording as the one I mentioned will help you understand what I mean. If you haven't the brass and percussion far beyond the violins, if you don't ear the low range rumble below the alto, if you are not surprised by the definition on the membran vibration very distincly from the timbale box itself 'tracks 4 or 6), the variation of friction over the string when the altist is coming from the upper to the second string (track 3)
then IMHO the system in front of you is probably missing real dynamic coming as I mentioned from energy and phase synchronicity.
HiFi is Bortolin (a brand sold some 20-30 years up to Canada but having missed capital to survive his success and restarting slowly in France)
Thanks for you advice. I'll try some other XLR connections but am not very optimistic when XLR is worse than simple unbalanced connections