I owned a pair of RS6 for a while. I would recommend a warm amp with powerful bass. The weakness of the speakers is that their bass never really comes out into the room to create a soundstage foundation, unless you have very good power in the bottom end.
If you can snag a Marantz PM15-S1, that would be a great combo. I used mine with a McIntosh MC7200 and it worked great - way better than a CJ MV55 did. Unison Unico would be a great choice as well. I also had a NAD C720BEE and would not recommend it, or similar, for these speakers because the top end would overpower the bass unless your room is tiny.
If you can snag a Marantz PM15-S1, that would be a great combo. I used mine with a McIntosh MC7200 and it worked great - way better than a CJ MV55 did. Unison Unico would be a great choice as well. I also had a NAD C720BEE and would not recommend it, or similar, for these speakers because the top end would overpower the bass unless your room is tiny.