RME interfaces can vary the sample rate by as much as +/- 5%.
So basically you have the vari-speed found on many multi-track tape-decks.
Helps when I'm struggling with those "rock falsetto" high notes that I
pretty much "wore out" back in the day.
I think in Reaper you can vary pitch, and or speed (its been almost a year since I messed with it).
Setup a "cue", track it, then bring the wav files back in CbB.
HTH