amp that can be bridged. Farting around with an old stereo receiver for a subwoofer amp setup is a bit silly to me. But that's just me. Also be sure to seal up the hole if you remove the plate amp.

"Would I be able to get adequate results by running the LFE directly from the AV receiver to the amp, and use the limited LFE volume control of the receiver to modulate bass volume?" No, get a power amp or a replacement plate amp, running a stereo receiver as an amp will not be very good.