I love my AV 5140's!!!! I've also got the AV 5120 as my center, a perfect match! I've used these speakers with Aragon and Acurus amps, but now I've got them running on Linn AV 5105's and it's much smoother, especially the highs and vocals. I had a Pioneer Elite receiver hooked up as my pre for a while, it worked fine, but since I'm heading to a full activ Linn system, I went and splurged for the AV 5103 (got it 2 weeks old, demo, for $4300!!! From a Linn dealer even!)
These speakers sound pretty slick with all the amps I've listed, but best with the Linn's. They will play well with low power, but really shine with higher power amps (200+). They are very dynamic, and I feel are a great speaker for both stereo and HT (My set-up is used about 50/50). They have a surprising amount of bass for the size footprint they have. Currently I don't have a subwoofer (I live in a condo so...) and I know the bass could be better, for HT especially, but it's more than adequate with just the 5140's. The bass really only lacks in the very low range. I had a pair of KEF 107/2's that accurately went to like 17Hz, with my Aragon 4004 MkII they literally vibrated status off the headboard of my waterbed, the 5140's don't quite do that, but for me that's not a problem. As I said, a sub would be nice for HT, I know I'll add one.....just not yet as I'm pretty happy with the setup now.
Note that I've only got one 5105 driving them, soon to be three in activ mode! By having each amp powering one driver after the Activ crossover, the sound is amazing! Many friends have heard my system and gone and bought Linn. My one buddy whose got the Snell B's as his fronts said to me when I was buying them "Are you trying to give me speaker envy?" 'nough said!
They also have some of the finest cabinet work I've seen! Mine are in cherry, they're gorgeous! Hell, even my girlfriend noticed how nice they look. She even comented on how good they sound! It's the first time she's said anything about my stereo! She was actually impressed at how much clearer the vocals were (Tori Amos-Boys for Pele) - smoother was her word too!
In short I love them! Drop me an Email if you have any questions I can help with.