speakers efficiency

Well I just wanted to point out that to have good dynamic range is essential to a good system. while you may only listen at an average 92 dbs but peaks could be much higher than this (especially on a well built system) this is the area where your amp could run into some trouble on a hard to drive speaker. These peaks could also (most probably) cold be at a frequency where impedence is also high, which is a real strain on the amp. For example using the above info (4 watt = 93db @ 1 meter) this figure probably means 90 db at listening position so in reality to listen at 93db average at listening postion you will need 8watts (with 8 ohm speakers). But for the amp to be able to handle dynamic peaks there needs to be headroom. If the peak is 12db the amp must cleanly without clipping put out 128 watts (8@93, 16@96, 32@99, 64@101, 128@103). Also factor in that this peak could be at frequency that the speakers impedence has dropped to 4 ohms or less even on a 8 ohm speaker and you need twice the 128watts or 256 watts@4ohms to cleanly play your wonderful uncompressed audio material at the average of 93 db at the listening postion. Of course good amps can also double in power as impedence goes from 8 to 4 ohms.

think i read somewhere that JA at Sterophile's database of past measurements indicate the avg sensitivity of the speakers evaluated by the mag has been 87

Duke,

You seam to know a bit about pro audio as well. Do you have any information on absorptive properties of crowds and rooms with large volume? I know that Master Handbook has some info on this but I have misplaced my copy.

Thanks!

THX = to be THX certified, equipment must meet certain standards such as sustained volume at 110db.
Ultra THX is even harder with 112db.
Many amps/speakers can't handle these loads. If your audio gear can produce 112db continuous, it means that you can play very loud, distortion free music.
My best amps aren't THX certified even though they can blow away the criteria (keep that in mind). 120 watt tube monoblocks into 94 db speakers.

Bignerd, I don't really have any experience in pro-sound applications; I just have played around some (maybe too much) with prosound drivers.

I have no specific knowledge of the effect of a crowd on room acoustics. I'd guess a crowd of people would be more absorptive than diffusive, such that the power requirement to meet a given SPL in a full auditorium would be several dB more than if the room was empty. And since most absorbers are more effective at short wavelengths (high frequencies) than at long wavelengths (low frequencies), the spectral balance of the soundfield would be tilted downward somewhat by adding a crowd of people. But I have no idea of the specifics of such effects.

Duke