Have the RME coupled with tube mono blocks in a full range system and nothing strident there. Had made some EQ settings in the RME but the biggest improvement as it turned out was adding a tube type preamp and not run direct into the amps. Others took any edge off using RME’s EQ.
Just a simple Schiit Saga saw a nice improvement in sound stage and dimensionality. Folks talk about the RME having a precision-type laser sharp sound but flat in presentation. Even using tube amps, it was a surprise to see the improvement adding the little Schiit Saga pre. It is significant in improvement and shows how capable the RME is and here with a rather inexpensive Schiit Sage taking the preamp chores away.
Before going into a heavy new DAC investment in a system with a pricey DAC, I’d try a preamp in the system first.