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!  


128x128diamonddupree
That’s good, but there is still not much to bank on with the MF amp regarding how it handles even 6 ohms nominal even with dips below that. So that still leaves things open perhaps to a significant extent. 6 ohms nominal may be a harder load than 8 ohms nominal with some dips...it all depends. You would have to try them with an amp known to be stable into 4 ohms which in most cases mean an amp spec’ed and preferably measured for 8 ohms that also doubles power as much as possible into 4. The MF might do that pretty well but there is nothing concrete to bank on that it would so far. If it could, you would think MF would document it and make the amp more appealing for more cases. Also the bass control offered by the very efficient Class D amps could still deliver a big difference alone. OR even a Class a/b with good documented performance into 4 ohms. Could even be Class A but that could get very big bulky and expensive to deliver the watts needed for headroom with less efficient speakers going louder.

On the other note, I have considered a miniDSP for use with my KEF ls50s and Klipsch sw308 sub and liked it very much so very interested in how that works out.

If we weren't such sound anal audio buffs we wouldn't even care about these details.  We'd just say hey we have a good enough system and call it a day.   Off course, no self respecting audio kook would EVER do that right?
@mapman guilty as charged! I'll let you know how the DSP works out. Thanks again! 
@diamonddupree Your post is such an appropriate post for what I was considering doing, that is get an amp with more power at 2 Ohms, the CODA #8 v1, v2, or v3 (600 - 1600 watts depending on version). I actually got some extra cash today for year end and would have been all over a new amp except for the results that happened yesterday. I no longer need a new amp.

I was reading a book on how to fix my issue. I ended up contacting the books author to remotely solve my acoustic issues. Take a look at my post here and to see what was done. Follow the links to see the graphs. This solution used a ROON Convolution file, microphone measurements of my room, and both REW and Audiolense software. Some very advanced stuff which I outsourced the to an expert. He has a business to do this type of work.

https://forum.audiogon.com/discussions/thiel-owners-2/post?postid=2066167#2066167

Send me a A'gon PM if you want to discuss any of this by email. 
@yyzsantabarbara very interesting and now I have a lot more reading to do! I just ordered a MiniDSP and I think next will be a mic that I can use to measure the speakers and room response. I think I'll probably still wind up with a new amp down the road but I'll have a much better idea of what to look for when I do. Thanks! 
@onhwy61 I downloaded a free SPL app, Decibel Meter, and holy cow, I guess I should be deaf by now! I'm averaging 100 db and occasionally hitting 105. And I'm still BELOW the level where I hear the soundstage issue I posted about. Maybe I should just listen at lower levels?!?!