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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!  


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yyzsantabarbara
4,699 posts
 
@diamonddupree Get the miniDSP UMIK-1 microphone for $100. Then download on a Windows 10 computer REW software. I am not sure if it works on a MAC.

The free REW software will use the calibration file sent with the microphone and setup your mic. The nice thing about this combo is that the REW software has special integration with the miniDSP mic. A real breeze to get going and I had never done this before.

You also need a test signal (maybe called a sweep signal). I used ROON to play the LEFT and RIGHT sweeps, one at a time. Once the data is collected by REW you have a lot of reports available including the SPL report. There are things like mic positioning, where it is pointed, and other things to do. Just contact the guy I referenced in the links and he will have you sorted out very quickly. Idiot proof instructions.
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diamonddupree OP
75 posts
 
@yyzsantabarbara I plan on doing exactly that. I already use Roon but haven't done anything with the filters yet so this should be fun. 
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diamonddupree OP
75 posts
 
One thing about the MiniDSP that I wonder about (if @yyzsantabarbara @erik_squires @tketcham or anyone else knows) is whether it will limit the upsampling available in Roon. I typically upsample to DSD 256, but from what I've been reading on the MiniDSP, it has a sample rate up to 192kHz, at least the USB input does. (Not sure if Toslink would be higher.) Anyone know if the MiniDSP limits upsampling and if there's a way to bypass it? 
yyzsantabarbara
4,699 posts
 
I do not know the answer to your upsampling question but I did stay at a Holiday Inn Express last night and learned something interesting.

1) I received a new Matrix Mini-i-3 Pro DAC yesterday ($899 MSRP)
2) Hooked it up and tried to get ROON via RJ45. Did not work since the ROON Certification is still a few days away.
3) I then used a very bad connection. Toslink from my very noisy computer to the Matrix using the TIDAL and Amazon clients.
4) Played a few songs and I am thinking this is rather good. I get to the 1976 song StarGazer from Rainbow and I am wowed by the sound. The percussion is hitting harder with better decay and it seems like the drummer is in the room. Awesome sound.
5) I switch to my Benchmark DAC3B ($1700 MSRP) on the better input of my preamp. It is connected to ROON with a microRendu. My best setup.
6) The same tracks are not the same sounding, It sounds more mellow and boring in comparison.
7) Only difference I can tell is that I have UPSAMPLING to 192 turned on on ROON. I turn it off and now only have my Convolution filter enabled. Boom, the excitement factor in the music is turned on instantly. Sounds as good as the Matrix, better in fact because of the better connectivity I have used.

End result is that I am no longer upsampling on ROON. Maybe that upsampling is not very good or I just prefer no upsampling.

Just an FYI.
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diamonddupree OP
75 posts
 
@yyzsantabarbara In advance of the MiniDSP arrival, I now have Roon upsampling set to 176kHz/192kHz, the maximum power of 2 upsampling the MiniDSP will handle. Whether the Roon upsampling or the active crossover results in greater sonic improvement, time will tell. That's some Holiday Inn, BTW! I guess those commercials were right. 
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