@atmasphere - Thank you, I truly appreciate your reply. Not using the Betas currently, but with a Rel line array either way can sacrifice a little bass for fewer headaches. I thought the Denon/Denon combo would be an easy fit.
I ended up purchasing the KAB Rumble filter.
https://www.kabusa.com/frameset.htm?/rf1.htm
Haven't had a chance to install yet, but initial impression is high quality and first class product and service. Won't be able to use balanced outs but worth a shot.
If this works as expected, I'll probably take the previous advice from @ ghdprentice and look for an AR PH8 and use the KAB rumble filter with it. Will report out after install.
Thanks to all.