My listening room absorbs sound like a sponge, so I have to crank up the volume quite a bit to get the concert-hall levels that I like. The Carvers sound great, but would run out of gas before getting to those levels. The BHKs have no problem with this. In terms of sound quality, the amps are pretty much even, with the Carvers having a bit more sweetness in the midrange.
The Ulfberhts are sensitve speakers but they do enjoy being hooked to powerful amps. Bass does indeed benefit from this. They take on an effortless quality when driven by large amps.