are all amps equal

First, get the amplifier/speaker match correct. The Usher BE-718 are not very
sensitive at 87db (actually measured 85db by John Atkinson in his Stereophile
measurements) , therefore they require a good amount of power. Although they
have a fairly flat impedance curve, their power requirements probably eliminate
most tube amps as the best match, including your ARC 150.2.

So, I would recommend buying a solid state amp (or chip/digital amp) with lots
of power (at least 200wpc into 8 ohms and 400 wpc into 4 ohms). Even 200wpc
isn't really quite enough power to give you realistic decibel levels on the BE-
718, but it will be a good start. If you can go to 400 wpc into 8 ohms, that's
even better.

Also, I would recommend buying a subwoofer since you're not planning to
replace the BE-718, which only go to 42Hz, and therefore are missing a
significant range of bass where much of the music lies.

Keep in mind that what additional power will do, everything else being equal, is to raise the volume level at which clipping occurs, and perhaps raise the volume level at which distortion starts to increase as the clipping point is approached. That's all it will accomplish.

And that in turn will depend on the size of your room, your listening distance, and the kind of music you listen to. Worst would be classical symphonic music, due to its wide dynamic range, and also obviously heavy metal or comparable rock music that, while it typically has highly compressed dynamic range, is listened to at very loud levels.

That said, I would think that given the speaker's 200W rated power handling, an amp in the area of 250 to 300W would probably be a good choice. But I'd feel free to deviate from that somewhat if it meant getting better sound quality or a significantly better price.

Concerning ICE and other Class D amps, one of their key strong points (aside from providing more watts per dollar, and reduced size, weight, heat, and power consumption) is high current capability, which does not seem particularly applicable to your speakers with their fairly benign impedance curve.

Regards,
-- Al

Thanks Tvad, and everyone else, I plan to go the Mcintosh path with 250 watts of more... Thanks again...

"Also, I would recommend buying a subwoofer since you're not planning to
replace the BE-718, which only go to 42Hz, and therefore are missing a
significant range of bass where much of the music lies."

Lowest bass or electric bass string is 41.2Hz (I think). Piano goes down to 27Hz (A) but is seldom used. Unless somebody listens to symphonic orchestra with big drums going down very low or needs special effects for the home theater than 42Hz should be fine (if its really 42Hz).

I'm perhaps missing something but there were known bass strings reaching 17.5Hz. I don't see (hear) any sense since it's not audible. Tvad - can you comment?

Keslerd - good choice - 352 or 402 should do it.