I'm off tomorrow to demo a pair of B&W 602 S3 speakers from a local dealer and possibly trade in the PSB Image B25 speakers I bought from him a week ago.
Can someone give me a 1 paragraph or less lesson (before I go to the dealer) on appropriately powering loudspeakers?
I originally bought a 2x80 W Denon DRA-395 stereo receiver to power these plus a Klipsch powered sub. There is a 2 x 50W (into 8ohms) Rotel RX-950XA stereo receiver available used that I could consider in this gear swap. B&W's tech sheet on these speakers recommends "25W -- 120W into 8Ω on unclipped programme", complete with British spelling. So 50W Rotel falls neatly into that range. I don't listen to music extraordinarily loud. Given that (and pending an audition of the Rotel receiver), what's to lose here? I understand that the Rotel, though used and rated 8/10, is a superior product.
Which receiver would you chose, and is the power difference an issue for these B&W bookshelf speakers?
B&W's are by nature a more difficult load to drive than the PSB's. How difficult depends on the model. However, if you like the sound of the amplifier with the highest available current, buy that one for any B&W. The dealer should be able to inform you what the amplifier requirements are for the speakers you choose. They should also advise you which amplifier is the most appropriate technical match for those speakers.
B&Ws typically dip lower in impedence than B&W readily admits. That puts more strain on the amplifier. PSB states 6 ohm nominal and 4 ohm minimum. PSB is know as being very honest in their stated specs. I'd believe that the B25s are easier to drive in this regard than the B&Ws. But that's only one spec.
Denon doesn't typically deal too well with lower impedence loads. When this happens, their amplifiers run hotter than normal and either shut down temporarily or clip. Rotel on average deals better with difficult loads than Denon.
Its far easier to ruin an speaker by underpowering it than by overpowering it. Distortion caused by clipping is by far the most common cause of blown speakers. Even if they're rated equally on paper, Rotel will out perform an equivalent Denon just about every time.
Power figures aren't the best indicators of an amp's performance. A lower rated amp may well double the real world power of a lesser amp. Under normal conditions with average efficiency speakers, most people use about 30 or so continuous watts from my experience. If your dealer has McIntosh gear, listen at a normal level and check the meters on the face. I bet they'll be around 30 watts, give or take a few.
Don't get me wrong, Denon makes a decent product. I just think Rotel makes a far superior product. They deliver what they claim to, whereas Denon has been know to inflate their numbers to make things more attractive to the general public.
But all that stuff doesn't matter if you don't like what the Rotel sounds like. IMO, the PSBs and B&Ws sound fantastic with Rotel. It depends on what presentation you prefer. Personally, I think the B25s are far better than the 602s. But that's my preference. Bring in your B25s (unless they have them at the store) and hear both the B25s and 602s side by side with the same amplification behind them. You should get a good sense of which you prefer.
If you don't need the tuner, you could get an integrated amp which will save you a few bucks and may sound a little better overall.
Also, make sure you have a good source. Forget about DVD players. Dedicated CD players sound a lot better.
I know I went over the 1 paragraph limit. But I could have made it into a single paragraph that was all over the place.