2 X Rel Carbons Incoming. Advice on powering?

Just placed an order for 2 Rel Carbon Specials on sale for boxing week, to pair with my B&W 802 D2’s and my Gryphon Diablo 300 amp(with DAC). I have zero experience with subs but am missing the gruntier B&W 803 D2’s that I upgraded from earlier in 2022, especially in my open concept room with vaulted ceilings. Why did I just jump into going with Rel vs other options like JL? Firstly because of Rel’s reputation when used for music, and secondly because Rel was the best option available from a dealer that actually commits to 100% refunds within 30 days on any product, if you are not happy. I know Rel has their 60 day return policy if you buy directly, but my other Rel dealer that said they can’t do demos or returns said Rel’s return policy doesn’t apply to my country… So I’ll have to break in as quick as possible if it doesn’t sound great right off the bat, which most speakers do not.

Looking forward to all the soundstage and “helping all of the frequencies not just bass” benefits that people and reviews go on about.  One thing that irks me about my B&W’s is how laser-focused the sweet spot is.  Move more than 2 inches and things are the tiniest bit off.  Someone else with the next generation of my speakers posted that adding a single Rel helped with off-axis performance, greatly.  Hope I find that to be the case.

I only have one suitable location for them, on the outside of each main speaker. Which according to Rel is the best position when using pairs. I also purchased two Bassline Blue high level cables. Will be purchasing Audioquest Hurricane power cords soon and connecting both directly to a single dedicated 20A circuit. All my other gear is powered by my Torus RM-20, which is powered by a second dedicated 20A circuit. This configuration creates a leaner sound than my amp plugged directly into the wall but also much cleaner and more solidly formed, so the weight of the subs should really help balance things out and offer the best of both worlds.

I’d be interested to hear of others’ experiences with subs, in particular any experience in terms of how to best power them, whether two connected to a single dedicated 20A circuit is an issue, and whether anyone thinks a conditioner on the outlet powering the subs would help and be worth the investment. Also, are the Bassline cables worthwhile? I can always return them if not :)