An alternate solution would be to find a MIDI file of the piece and mute the piano track. You would need some sort of basic MIDI editor though, so you can actually see the individual tracks. Good thing about MIDI is you can adjust the tempo to whatever you want. https://www.classicalarchives.com/
I wouldn't recommend this method for the Schumann concerto... it needs to breathe! MIDI is so suffocating -- might work for early classical period concertos, though.