I own a pair of the Gen V's the predessesor to the 500 and 501. I use a VAC Ren 70/70 tube amp with them and they work well and the servo amp cranks out all the bass you could ever want. Good clean bass too. My amp is rated at 65 WPC and you can play ANY music on them as loud as you want with no strain in my 14 X 18 room. I cannot reccommend the speakers enough. In fact there is a pair of Gen V's on sale in the speaker boards right now, a bargain price too considering they retailed for $15K!
