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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
22,509 posts
 
Yes but the topic was total amps not power so # amps per channel x 2.

Class D amps are most efficient by a large margin. That’s their biggest claim to fame. So they are inherently better at delivering more power and current than others. Just like more efficient speakers are better at going louder with less.

You will have to take that argument up with bel canto and their published specs for PEAK amps and power onto both 8 and 4 ohms. That power double couldn’t happen without the hefty # amps to enable it. If more than enough, then better safe than sorry. Right now the OP still sounds sorry so maybe better to be safe.
audiorusty
287 posts
 
Proper installation of your MiniDSP would be between your preamp and amps. IOW you would connect the left and right outputs from your preamp to inputs 1 and 2 of the MiniDSP. You would then send two of the four MiniDSP outputs to the inputs of your Musical Fidelity amp and one of the remaining MiniDSP outputs to your sub. Technically you could send both of the remaining two outputs of the MiniDSP to the your sub as long as the sub has both a left and a right input but I doubt if you would notice any difference. 
diamonddupree's avatar
diamonddupree OP
75 posts
 
@atmasphere the JL sub that I have makes it very easy to set up with auto room correction. It comes with a mic that you place at the listening position, run a test sequence and the sub's internal DSP corrects for the room modes. I've never had a problem setting up the sub anywhere I've placed it. In corners, against wall, midwall. Once I run the room correction software, from the listening the position, there are no nulls, peaks or modes as far as I can tell. 
diamonddupree's avatar
diamonddupree OP
75 posts
 
Thanks @https://forum.audiogon.com/users/audiorusty. My DAC is my preamp. The Brooklyn DAC+ is both a DAC and a preamp. But most everything else you said applies. I'll take the analog outputs from the Brooklyn and connect them to the analog inputs on the MiniDSP, then the analog outputs from the DSP to the MF amp. Only thing is, I run XLR cables to my sub because when I've run RCA, there's a low-level hum from the sub that completely goes away when I use XLR cables. And the MiniDSP doesn't have XLR outputs. So I'll have to stick with the XLRs going from the Brooklyn to the sub (L & R). 
erik_squires
16,410 posts
 
I really like the room correction in the JL Audio, doesn't it have a high pass output as well?  I'd go that route before adding more gear.
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