are all amps equal

"Although they have a fairly flat impedance curve, their power requirements probably eliminate most tube amps as the best match"

Tvad, I thought speaker/tube compatibility was all about the impedance curve, and that low efficiency speakers, with benign impedance curves, simply required more power, regardless of whether the amp is tubed or solid state. I'm not saying that you're wrong, I just want to understand.

I think the room you are using has a lot of input in the sound factor. What is the size of the room, flooring type,etc.
I don't know any thing about Usher speakers, but this might help those who do give a better answer than what I've read so far.

I have Magnepan, Thiel,Meadowlark and Soliloquy speakers teamed with McIntosh,Bryston,Aragon, Classe , Rotel SS amps and pre's and a CJ tube system.

It takes a lot of playing around to get great sound, move it to a different room and it sounds like S**t.

I have a great wife that lets me set my up systems in four rooms, not to mention two Plasma tv's on separate systems Harman Kardon, Yamaha, Def Tech and several subs.

By the way, I think subs are the hardest to balance in a system for great music.

P.S.
I think my wife has four boyfriends to make things even.

the room is 12 by 15, short cut carpeted floor, and two 2 by 2 foot sound panels in each corner (total of eight) all furniture is fabric... with a french door size opening on the rear wall into a larger room.

as far as extension, definition and etc the sub adds, most of the time I prefer the Ushers alone... the sub is not very "tight" as I prefer, that may be definition.
I don't understand everything I know...

Dcrookham53 - I'm afraid I might be one of them - she often mentions cruel husband that has systems in 4 rooms. Sorry.