I am glad the efforts turned out to be nice for you!
From my perspective as a recording engineer with several decades of experience:
Piano is a good reference on one side, because the relatively steady tones tend to sound annoyingly resonant if something's wrong with the room acoustics.
On the other hand piano is not a good source to check for sound balance, because every piano, every pianist and every recording sounds different.
There is no 1:1 recording of a piano.
For classical music, orchestral string enssembles are the most demanding for natural colors.
Finally, one has to use various recordings to evaluate if everything is correct.
Over the time, listening to a wide variety of different recordings you will find that even there are recordings that are simply not well made, then that's nothing to blame on you setup.
It's simply, the closer you come to a good acoustics, with good loudspeakers, the more different various recordings will sound.
Bad acoustics tend to wash all into the same bath.
If you want to have fun, you can try to find out which digital connection sounds better.
Once you found that one or the other sounds superior you have been caught in the placebo trap.
You just have to read about it before doing so to gain a little of pre-justice and placebo will work out fine.
In fact, every digital connection sounds exactlythe same as long as the transfer of data is uncompromised, and the device at the receiver side has a proper reclocking, which is 100% the case with the RME stuff.
The bits don't care about going through copper, silver, gold, plastic or glass fiber or air, they just stay zeros and ones.
If there are errors they are clearly audible, as cracks.
Nothing can make the ones and zeros per se more musical.
Have a nice time enjoying your newly gained fidelity!
