What preamp

I kind of agree with ddd1. For me, if you can't get a really good preamp, then don't use one. Preamps can be very problematic , but if you can find the right one, I think it will sound better than not having one.

More importantly: "I would like to have something to calm down the bit brightness of the Pollk Audio RT's that I've had heard they have."

Are you kidding? I don't mean to offend, but why would want to fix a brightness problem your speaker has because someone else says they are bright. That's just crazy. What do you think? You're the one that has to listen to them, not someone else.

Thank you jkj25, would you recommend any preamp, my amp has balanced imputs, but the Emotiva preamp doesn't.

Your amp is not a truely balanced amp so it wouldn't matter if you use single ended or XLR connection.

IMO A9's and Emo gear do run a bit brighter on the top end. I've owned both and that was my experience with it.

Are you sure that the XP-A2 is not balanced ?

Well, anybody is going to recommend any preamp that is know to work good with Emotiva gear?