What does moving from a 150 watt amp to a 400 watt amp get you?

1)The reference to SPL (sound pressure level) falling off at 6 db per doubling of distance applies to most non-planar (box type) speakers. The rate of fall-off for planar speakers such as electrostatics is significantly less.

2)More often than not sensitivity is specified as the SPL produced at 1 meter in response to an input of 2.83 volts, rather than in response to 1 watt. For an 8 ohm impedance those results will be identical, since 2.83 volts into 8 ohms corresponds to 1 watt, but for a 4 ohm impedance the SPL produced in response to an input of 2.83 volts will be 3 db less than if the spec had been based on 1 watt, since 2.83 volts into 4 ohms corresponds to 2 watts.

In any event, Stereophile measured the OP’s speakers as providing an SPL at 1 meter of 89 db in response to an input of 2.83 volts, which corresponds to 1.6 watts into what I would consider to be its 5 ohm impedance (see my earlier post regarding the 5 ohm figure). 1.6 watts is about 2 db more than 1 watt, so the speaker will produce 87 db in response to an input of 1 watt. The 240 watt capability of the amp into 5 ohms (again, see my earlier post) corresponds to about 24 db more than 1 watt. Two such speakers listened to at a distance of about 10 feet when driven with 240 watts will produce an SPL of approximately 87 + 24 + 3 -10 = 104 db, very close to the 105 db minimum recommendation provided in the paper.

And as I mentioned earlier, an amplifier capable of providing 400 watts into 5 ohms would add very little to that figure, 2.2 db to be precise. Unfortunately, IMO, it appears that very few of the responses by the others have focused on the OP’s situation in a comparably specific manner.

All of this assumes, btw, that the speakers are capable of handling these high power levels without significant thermal compression or other non-linear effects becoming significant. I have no knowledge of the maximum power handling capability of the Revel Ultima Studio 2, or of how well it would perform as its power handling limit is approached.

I would add that while I personally listen to a lot of classical symphonic recordings that have been engineered with minimal or no dynamic compression, and consequently I have stated in some past threads here that 105 db at the listening position is the minimum peak volume capability of any amp/speaker combination I would consider (which happens to coincide exactly with the paper’s minimum recommendation), my perception has been that the majority of audiophiles do not listen to recordings that when played at their preferred volume levels would come anywhere close to such high peak levels. With peak levels not exceeding even 90 db in many cases that have been mentioned in past threads here. I believe the main reason for that is the high degree of dynamic compression that most recordings in various genres, especially pop and rock, tend to be engineered with.

Thanks again. Regards,

--Al

I'm sorry to say that most of the responses you've received are not useful, and some are nonsense.  (There are some good ones too, so don't everybody feel insulted.)

I'll try to help...  In general, more watts are not needed for more volume.  They are needed for more 'headroom'.  In a musical recording, the transients (leading edges of any sound) are MUCH higher amplitude than the rest of the signal.  Having plenty of headroom allows your amp to produce those (fraction-of-a-second) transients at full volume without attenuation or 'clipping'.  That results in a much richer, more robust and more REALISTIC presentation.

It's also true that less efficient speakers will perform better with plenty of wattage & current, because they simply need more power to 'sing'.  I tend to like the sound of low-efficiency speakers mated to powerful amps, but there are many exceptions (& that's my personal taste).

That being said, your Revels are rated at about 88 dB sensitivity w/ nominal 6 Ohm impedance.  That is a moderate, rather than difficult, load, and should not require 400 W/ch.

What's more important is the QUALITY of the amp!  The Ayre V-5xe is a nice-sounding amp. You could easily find a mega-watt amp that is not so well-designed... and take a step BACK in sound.  I would try to audition the Revels with a more powerful amp before spending any $$. You may find that there's no real advantage.

BTW... what pre-amp are you using?  Have you tried a tubed pre-amp?  I've had great success matching solid-state power amps with tubed pre-amps (incl. my current system). That gives you the tight, well-controlled bass associated with solid-state as well as the beautiful mids & highs that only tubes seem to provide.

Anyhow... I hope that helps. 

...for a 4 ohm impedance the SPL produced in response to an input of 2.83 volts will be 3 db less than if the spec had been based on 1 watt, since 2.83 volts into 4 ohms corresponds to 2 watts.

...for a 4 ohm impedance the SPL produced in response to an input of 1 watt by a speaker whose sensitivity spec is based on 2.83 volts will be 3 db less than if the spec had been based on 1 watt, since 2.83 volts into 4 ohms corresponds to 2 watts.