If just using them with digital outs, identical.
If they sounded any different with digital outs, your DAC sucks, which surely isn’t the case with yours.
Marantz looks to have the best pre-outs for processor use, Denon is still OK (get an X3400 and just use the pre-outs), but Yamaha is not good, can’t even do 2Vrms and not as clean. You want Audyssey for your system, even if just for the subwoofer (you can have it correct everything or bypass the mains). All the Denon/Marantz models of the same range use the same AKM DACs, so the digital aspect for surround sound will be the same. For the analog inputs from your DAC, the Marantz may be cleaner though.
I would also recommend demoing a high end SVS subwoofer (free returns), and if you like it more than your REL, get a high end Rythmik or PSA subwoofer (they charge for rerun shipping, but that helps keep the prices low).
No need to go crazy for an amp for surrounds, any Emotiva would work.