Dynamic Headroom - Low v High Power Amps

One of many things that confuse me is dynamic headroom. I get the basic concept but wonder about the practical conditions where it makes an actual difference.
Specifically I’m thinking of low vs high power amps. I have a pair of M1200 playing through 90dB 4 ohm Spatial M4 Sapphires. Sounds great. I just bought a Schiit Lyr headphone / preamp and Gjallarhorn 10wpc speaker amp for the desk top. Also sounds great playing through the same M4s.
My torture track, as a reviewer described it a few years ago, is “Luminol” (Steven Wilson, “The Raven That Refused to Sing and Other Stories”), which I’d think is a good test of dynamic headroom.
To compare the systems I played this track at uncomfortably loud levels, which for me in my space is upper 70s average with 80s peaks (unfortunately I didn’t record actual levels). I honestly could not tell any difference in the into drum attack. Overall I thought how the 2 very different sets of gear presented this and other tracks was very similar.
Maybe I’m just deaf to what others might find to be significant differences but I’m having a tough time reconciling the dynamic headroom argument for high power amps. Besides general curiosity I’m wondering if my listening preferences are better suited to a low power system that does more with less.

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Allan,

As you’ve discovered, power amp needs/advantages are overrated when you listen to music at lower levels (70-80db peaks). With your 90db rated M4’s, your 10W Gjallarhorn amp will still provide you with +10db of clean power to cover most dynamic peaks!

Where issues come into play is with inefficient speakers, being pushed with low power amps, trying to play at much higher continuous listening levels, with music that exceeds +20 to +30db of dynamic musical peaks (ex: live orchestral acoustical music)!! In these instances, high power amps that can safely cover these extreme dynamic peak sound levels without clipping distortions will be very welcome (like your M1200’s)!!

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The Decibel (dB) Scale & Audio Rules 101 | Audioholics

  • Doubling the power output (watts) will result in a 3 dB increase in loudness.
  • A ten times increase to the power output will result in a 10 dB increase, or sound that is twice as loud.
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Most systems won’t be twice as loud no matter how many watts you have, speakers have a maximum level.

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Many thanks guys. I need to keep the basic relationship in mind as well as dB reduction with distance. I’m sitting about 2m from the speakers. It’s too early for inverse square laws and solving matrices but the back of the napkin says 1w still nets about 84dB at my LP.
In the Audioholics article the editor notes the 6dB reduction is related to anechoic chamber measurements. Real world is closer to 3-4.
It’s really sinking in that my set up, in my relatively small space (11’ x 14’), and my listening preferences lends itself to a low power system, even if I want to swap in my other less efficient speakers (85dB). Quality of watts over quantity. Something to think about…
Thanks again. This has been quite helpful.

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