IOTAVX Sa3 and Pa3 in bridge mono mode/subwoofer

I’ll try and make this quick. I have the iotavx sa3 and pa3 bridged together. Sa3 right speaker. Pa3 left speaker. I recently bought a pair of rels t5i. Connect high level to monoblock per their instructions. 2 issues.... and i didn’t post in subwoofer forum because Rel said this was an issue with the amplifiers. Basically I was hoping there was someone out here has the iotavx stack and has successfully hooked a pair of subwoofers to them. When I turn the amplifiers OFF... the rels get very loud and the woofers vibrate like crazy. Rel says they think it’s a issue with iotavx...and its rare. And it Will probably be unsolvable :(. I’m new to this and don’t know if this can effect the sound when the amps are on...because I need to have the gain and crossover way past where rel says they should at 2 o’clock. I cant really get an answer because rel isn’t very familiar with iotavx and iotavx customer service is practically nonexistent.
Have you found any resolve to your issue? I have the Iotavx SA3 & PA3 as well. I have been thinking about purchasing a Rel subwoofer too. Good luck and I hope it works out!
I have not. Sorry.
Im currently using low pass from each Rel to each pre out...via y adapter :/

One could just use the sa3 as a pre amp but I’m stubborn. And I like how the stack sounds.
I also prefer the high pass on the rels. Bass is better, sound is better. :/
I suppose there are a couple things I haven’t tried... those 2 things are:
Upgraded cables and..
Someone suggested soldering the BLACK wire on the rel cable to the outside shield of a rca plug...and connecting them to unused inputs on the sa3. Rel claims there’s no difference in that than there is using a rca from sub to input(which didn’t work) I haven’t given up...just taking a long break and trying to to enjoy my music.
I even talked to Ian..the IOTAVX’s head engineer and ceo. He called me from England and we talked for almost an hr. He called because I sent in pix of the way rel told me to hook it up for high pass. He couldn’t believe it and was basically like what the hell is that. He flat out said he hasn’t seen that kind of connection since the 70s. Then he went on to say...I developed a very good sub out...use it.
Still...I a/b tested it. And to my ears...high pass sounded better.
Keep me posted man. I’d like to know what u decide to do. Which rel are u thinking abt?
I was thinking about the REL T/5X is what I would like. I also have the Iotavx SA3 & PA3 combo and also run them in bridge mode. I just watched this video today and thought about your situation.