What is Floyd Toole saying about extra amplifier power and headroom?


I've been reading Floyd Toole's "Sound Reproduction The Acoustics and Psychoacoustics of Loudspeakers and Rooms" and came across a passage that I wish he went into further detail about. It has to do with whether having amplifier headroom has any noticeable improvement in sq. He happens to be talking about getting the bass right in small rooms, but in doing so, he also touches on the use of a larger amp for extra headroom: 

Remedies for unacceptable situations typically included spending more money on a loudspeaker with a “better” woofer (without useful technical specifications, that was a lottery of another kind) and a bigger amplifier (for useless headroom ...

It's the last part ("useless headroom") that I'm curious about. I have notoriously hard-to-drive speakers (Magico Mini IIs). Although the recommended amplification is 50w - 200w, in my experience, that's a bit of an underestimation. I'm driving the Minis with a Musical Fidelity M6PRX, which is rated at 230w @ 8ohms. (The Minis are 4ohm.) The combination sounds excellent to my ears at low to moderate listening levels, but I notice a slight compression in the soundstage at higher levels. My listening room, while small, is fairly well treated with DIY panels made from Rockwool, sound-absorbent curtains, and thick carpeting. So I don't think I'm overloading the room. But I have wondered if an amp with far more power than what's suggested (more headroom) would drive the speakers with a little less effort.

Those of you familiar with Toole or with driving speakers with power to spare, what are your experiences? If I went with, say, a pair of monoblocks that drive 600w @ 4ohm, would the extra headroom address the compression I'm hearing at higher levels? Or am I wasting my time and, potentially, funds that would be better spent elsewhere? 

Thanks!  


diamonddupree
More power and headroom alone may help get bass right especially at high SPLs by avoiding clipping, but alone is most likely not a complete solution in most cases.

Current delivery and related damping factor of an amp also contributes. How much will vary but more difficult load speakers generally benefit from more current delivery capability to control the bass better, meaning a beefier amp than one perhaps of similar power but less current delivery capability. Power and current are not the same thing.

For example Magnepans are not very efficient and benefit from more power but not nearly as much from more current than many dynamic models. Smaller dynamic designs with more extended bass tend to be the least efficient and to also present a more challenging load, so more power and current is typically the key there.

OF course then room acoustics are a big factor for bass frequency response and all that goes with that as well, but that has nothing to do with the gear itself. Once you have an idea of approximately where the speakers will be located, its much easier to get the gear matching right first, then deal with the much harder room acoustics after. Having flexibility in final speaker location is a big help when it comes to bass and room acoustics in general.
Thanks @erik_squires, IMO, all speakers, even floorstanders, could use a subwoofer and I have one in my system, a JL Audio Fathom 110. It has a 900w class D amp and auto room correction. I have the LP freq. on the subwoofer set to 38hz; the Minis go down to 37hz. With the room correction and the LP freq where it is, I feel like I have the sub and satellites integrated pretty well, at least to my ears. I’m using a single sub because I don’t think the room can handle a second one, and after reading Toole, it seems like I have the recommended placement just about right.

Edit: Here's my room:
https://systems.audiogon.com/systems/9016

What do you think the effect would be of adding extra headroom? Or should I be looking more at low noise and low distortion?

Thanks for the links. I’ll read them now.
@mapman very interesting. So what would I do to increase current delivery? I've done a fair amount to treat the room and I feel like my sub is already pretty well integrated. Here's my room:

https://systems.audiogon.com/systems/9016
 
Hi OP:

Yep, this will integrate well, but leaving the mini's to go down to 40 Hz won't really improve your dynamic range.

Lift up the crossover frequency to 80 Hz.
So a couple of things.  If you don't have a high pass filter on your main amp, the speaker and amp will be forced to reproduce the lower octaves, even though you won't hear it.

Not only does this limit dynamic range, but it increases distortion heard from your mains, both harmonic and Doppler.

If you keep your mains at low volumes, this is not a problem, but if your goal is to use the sub to increase bass AND dynamic range, the high pass filter is a must.