Set the preamp to MONO L+R, and connect either output (L or R) to the power
amplifier input.
The "low filter" is a first order 70Hz, not a rumble filter. Could be useful for some purposes, I suppose.
If you have ONE mono amplifier, set the preamp to "Mono" and take one RCA cable to the amplifier. Connect it to either the Left or Right output on the preamp...doesn't matter which as when the preamp is set to Mono, the signal is the same.
You should most likely connect it to the Low Filter RCA input, as I can't imagine your Dynaco wants to see the really low (below audibility) stuff your Accuphase is capable of passing along
Nice gear btw!
Then you connect one of the L outputs to an amplifier and the corresponding R
output to the other amplifier. I understand there are two pairs of outputs
to allow you to drive another stereo power amp, just leave the second pair alone.
Added note: I guess I wrote essentially the same thing as redcoates7. Regards.