Just checking in to say that I hear beautiful bass comes out of 901 balance mode with high gain on when pairing with 650... Very satisfied and beautiful sound. Imho, Its better than db2 + intruder (full balance) if we talk about portable setup.
Agree to other suggestions of finding the right can/iem for the music you enjoy and good luck.
Do you feel the 901 drives the 650 better in balance mode over SE?