I’ve never heard the d90 so can’t comment. I have the RME in a second system with Teddy Pardo power supply. I almost sold it after it was broken within a month or so of ownership. It was 2D and analytical and not enjoyable, lean mids and not much harmonic richness like someone described above.
The strange thing is it’s very dependent on the power cord going into the amp it’s plugged into which for me is a CJ el34 amp. Once you find the right cord I goes from very digital to very smooth with rich tones, I hate this term but it was night and day. I run mine on NOS with everything flat.
I was going to sell the RME and just by accident I put the Harmonic Technology Magic power cord in the amp and the light presentation RME became big and full and analog sounding. Which is not how most describe the RME including myself. I also had an old Haronic Technology Fantasy 10 power cord which did the same thing just maybe a smaller degree but still a pleasant change. I have a JPS labs going into dac (Teddy Pardo) and Acoustic Zen Silver Ref 2’s going out of RME. I really think the RME is very cable dependent.
If it wasn’t for the HT cable going into the amp the RME would be long gone by now.