enough watts to drive these speakers? Help?

My listening room at home is just about the same size as your friends. My current system there is Soliloquy 5.3 speakers which are 90db floorstanders, paired off with George Wright Mono 10's which are 10 watt monoblocks (push-pull 2A3 based amps). Plenty of power for the size of the room, but as has been said, don't expect chest-pounding bass. My system can play at very 'satisfying' volumes and remains engaging at low volume as well. YMMV depending on which amp and which speakers you end up pairing off. Being a 2A3 based system it is all about midrange and leaves a bit to be desired in the low end. I've tried in the same room pairing off 8 watt 300B SET amps with 89db Silverline SR-17 monitors. Though they did sound wonderful at very moderate volumes, this combination did not work at all well when the volume went over about 88db (I'd guess). Numbers don't always tell the whole story. But I think the general speculations and expectations given his taste for jazz is a good bet for a nice solution if done with care and consideration for synergy.

Marco

Good points Marco. My comments referencing the 300B pertained to some "manufacturers" claiming that their single 2A3 per channel ( or similar tube ) will do 8 - 10 wpc. Since you're amp is not a SET and each tube is only doing half the work, it is possible for two 2A3's to make that kind of power.

The reason that i mention this is that i remember a speaker manufacturer measuing a certain SET amp that was advertised at 8 wpc. The person that had bought their speakers was using this amp and complained that the speakers weren't as sensitive as the manufacturer stated. That is, 8 watts should have driven the speakers, but it wasn't. The speaker manufacturer wanted to see what the deal was, so they checked the amp. When it came down to it, the amp was having a hard time doing 3-4 wpc, which just wasn't enough. As such, one should look at the tube compliment of the output stage along with the rated power output. If you've got one tiny tube per channel, don't count on ore than a very few watts at most. Bigger tubes typically have bigger plates and can pass more power, offering higher output levels. One can also achieve this by paralleling multiple tubes or running multiple tubes in push-pull fashion ( like Marco's amps ). Buyer beware... Sean
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Fatparrot,

Just saw your comments.
6dB loss in SPL per doubling of distance is correct! We are not talking about a power measurement here; rather, a voltage measurement when we read off SPL on a meter. Hence, 20*log() rather than 10*log(). Another thing is that since it is a ratio (SPL at 1m vs. SPL at 2m) when we do a divide operation, the impedance cancels out.
Hope that this clarifies.

Bombaywalla, I understand where you got the 6 dB figure (voltage), which can throw confusion into the mix, depending on whether we are talking about voltage, or power readings. But I thought that actual acoustic sound waves (spl) were a measure of POWER, and not voltage. The spl meter converts this to a reading which represents dB's of power not voltage. But I will do further research, since you now piqued my curiosity!

Think of it as surface area. As the distance doubles the surface area quadruples...equal to -6dB/unit surface area.
I didn't read anyone's reminder that sensitivity values are usually expressed at 1k, which can be far less meaningful unless one knows the low frequency rolloff (and impedence). Since it's possible for a "high" efficiency speaker to have much lower response, let's say, at 50Hz than a lower efficiency one with flatter bass, one can indeed be fooled into predicting that a low power amp might have an easier time with the former...especially if a low impedence couples with a large phase angle diff in the bass. So it's not so simple...especially with a tube amp.