Peachtree Audio Nova - No subwoofer connection

I just switched from speakers (Martin Logan Ethos) needing no subwoofer to a pair of monitors (Reference 3A MMC Serie) which have an advertised lower limit of 40-42 Hz. This is fine for most of our listening but there are occasions, like when watching movies, when additional bass would be nice. I have a Polk Audio Micropro 4000 which seems very capable but the Nova has no dedicated connection for a sub. I talked to a Peachtree technician who said the only way to connect a sub is to use a splitter at the RCA pre-out connection dividing the signal between the Peachtree 220 amp and the sub. I tried this before and, of course, the sub works fine but it changes the overall sound in a not good way.....and I'm not good at judging minor changes.

I also use the Behringer Ultracurve 2496 in the system and separating the signal this way bypasses the sub's signal from the equalizer so auto room adjustments won't include the range of frequencies that would be produced by the sub. I suppose that if there was a dedicated sub out connection the result would be no different. Because base frequencies, though, are a big part of adjustments for the purpose of room equalization, this is a problem.

Because the 2496 has an unbalanced 1/4" aux out" it crossed my mind that it could be used for a sub. The manual doesn't seem to address this and I've not found discussions about this on the Internet. I've also not been unable to establish communication with Behringer for their help.

There's a good chance that I'm off base on some of these assumptions about this all works but if anyone has suggestions that might help with this dilemma it would be much appreciated.