I use an Elite Plus in my upstairs system. It’s not particular about what speakers it powers; if the drivers in your Polk 7’s are still working well, I wouldn’t be in a rush to get rid of them at all. If and when you do, there are plenty of options though. One brand that might fit quite well with it would be Human Speakers (humanspeakers.com) - he makes his own line and also rebuilds Genesis. Check out his Model 81. I am using my Elite now with a pair of Sequerra Met 7 Mk II’s and a small REL subwoofer - this is an extremely satisfying combination and is not embarrassed by my “big” system but the Sequerras are now hard to find. Lots of stuff out there though, depending as always on budget.
BTW I once owned a pair of Polk 10’s, the original version with Peerless tweeter. My ears have hopefully evolved since then but at the risk of a bit of audiophile-ridicule I will say that if I were stuck on a desert island with a pair of those and no other speakers, I would not feel that I was suffering. I think the 7’s are probably better within their frequency limits as they are not fighting that big floppy cabinet that the 10’s have. So again, if they are in good shape I would think twice about replacing them, and beware the sideways move.