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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
mapman's avatar
mapman
21,886 posts
 
If you can try the Bel Cantos with no obligation that would be worthwhile I think. I am a big fan of Bel Canto and their products are typically highly regarded in reviews. I also have a c5i digital integrated (60 w 8 ohm/120 to 4) in my smaller family room 2 channel a/v system with my smaller Ohms.

Using a crossover to offload work from the monitors and have the sub pick up the slack is a very reasonable thing to try.
Can’t say what will sound best. Only you can tell. But those are both very reasonable and sound things to try.

Sounds like your MF amp can deliver twice the juice to 4 ohms at least for short peaks that require it. That’s not uncommon and still a good thing. How good? Would need some measurements to know and compare.
diamonddupree's avatar
diamonddupree OP
75 posts
 
@mapman thank you! Very helpful! 
volumizer
86 posts
 
Agree with Millercarbon about speaker efficiency. Disagree about headroom. I like having options while listening. High efficiency, low distortion speakers, with crossovers tuned to your taste, plus an amplifier with low distortion and more power than you need, is the beginning of getting it just right for any audiophile.  It’s important to sound good at low levels, medium levels and high levels. 
The perfect system will be able to play distortion free, louder than you ever want to hear it. 
fuzztone's avatar
fuzztone
5,508 posts
 
Headroom is for peaks. Without peaks you have compression.
Talk about useless!
mapman's avatar
mapman
21,886 posts
 
Dynamic headroom means having more power than you need.
If you don’t the amp may clip during dynamic peaks.

If I ran the servers where I work without the dynamic headroom needed to handle peak workloads, they would crash and I be out of a job.

Same concept. Dynamic headroom is your insurance against clipping and yes you need more power and often current to get it with less efficient speakers.


More efficient speakers may still present a difficult load and require more current to sound their best so that alone is not a panacea.

Very large speakers are typically more efficient. Some are also easy loads, some less so.

If you want smaller but capable speakers like Magicos, the amp has to be able to up its game to deliver the goods.

Either way or anything in between can work out top notch. You just have to get the system matched and set up well to meet your needs.
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