Have you been able to get the sub dialed in to what you think is acceptable? From what I have read on this subject it seems to me Rel flies in the face of conventional thought. If it were me I would try the low level input and crossover the M60s in the 60Hz range. If the 60s are +/-3dB (Hz): 37 - 22 kHz and +3dB- 9dB (Hz): 27 - 22 kHz why would you want to have the crossover at 25Hz. To me it would seem there would be a hole in the lower part of frequencies where the M60s leave off and the Rel (set to 25Hz) picks up. If you can try to do some frequency sweeps and see what you come up with
