I ran my P3ESR's in my second system, with a few amps from Croft, the Bel Canto s300i to a highly modded Quad 405-2 and the different amps made obvious changes but always sounded good. The room was 10' x 12' and I was sat around 6' away from them. I ran them with a Rel Strata sub.
I then finished the room I was putting the system in, this room.....
They sounded absolutely shocking!!
They were so bright and hard sounding.
There is a sub behind the sofa and no matter what amp or cable I tried it sounded terrible.
I had a pair of Quad S2's boxed up to move on, put them back in there and bliss. They were superb.
A pair of £50 Celestion Ditton 15XRs sounded better, even some Monitor Audio Bronze 2's that I used for watching TV with sounded better.
They need a smallish room, and lots of soft materials in there imho, ask them to do just a bit too much and they fall apart. They are small speakers, and work when used as such imho.