Pair of Rel S510’s or Carbon Special’s?

Hi, with respect to advice I get on these boards, I pay attention to individual advice, but I ALWAYS ultimately pay attention to consensus.  I find it is the only reliable approach and it has led me to some very positive results.  For example, I’d never heard of Gryphon before and was failing to find an amp that made my speakers sound better than mediocre.  Then I heard about Gryphon in these boards, and it seemed like almost 100% of people were going on about how great The Diablo 300 was.  Even the “My long list of amplifiers” dude had a spotlight on the Diablo 300 for a while, saying there was nothing, separates or otherwise, that bettered the Diablo for $50k or less.  At that point I made the effort to trial the Diablo and I was stunned at how my speakers came alive, with zero annoyances in the tonal balance as I was finding with every other amp / preamp I was testing.

All that to say, my goal is quality and I am not at all tied to Rel. Going back to consensus, the reason I started with Rel is there seems to be a lot of folks who say they are great.  That said, I’m sensing there may be more people who aren’t so happy with Rel.  In the case of my Diablo 300 amp, I think I’ve found maybe 3 posts tops where people aren’t liking what they hear, amid a sea of praise (which I would happily add to).

@nyev REL makes fine products; they're also quite popular. I love my REL. But the issue for you is the constraint placed by positioning and whether REL's -- for their price and lack of flexibility with settings -- can get you where you want to go. You're hearing from those who love their REL and some (like me) who love their REL but don't think that a REL is necessarily capable of working in every situation.

when i get a notion to respond to the OP's slightly unusual goals or the entusiastic brand fans you chime in and I chuckle in agreement. 

I so empathize in dealing with the shear stoutly centerd weight of most subwoofers and ones ever diminishing abilities. My subs and Bass amps/cabinets are on wheels. I don't leave the house with anything bigger than my tom drum sized upshot 10" cabinet and cigar box sized switching amp. 

I'm enjoying a notcable differnce in the presentation of my two main system subs which are now on DYI foam topped platforms with large soft foam casters. A stunning reduction of low frequency energy migrating through our homes structure and slightly better definition at the listening position. 

Anyway, ask for help and bend those knees.

This reminds me of a Kamala Harris speech.

OP was particularly asking for comparisons and feedback for two specific REL models. That's why some of us stayed within the parameters of the initial ask. It doesn't mean we believe that REL is the only game in town.

Anyways, I still feel that driver speed is much more important than sheer bass output for subs dedicated to two-channel listening. This is exactly why REL is preferred over other HT-focused brands, despite much lower power output. But I agree that they need to do better to help with placement flexibility. I don't understand why they only provide 0 or 180.

+1