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How could 100 Watt class a has more head room than a 300 Watt amp Class AB

Put aside which brand or make.
I put two amps into a test, both highend amp came from the same manufacturer.
Both double down the power with half of the impedance load, and THD is about the same.
Regardless of the size and cost difference, from a pure science perspective.
300 watt in theory should provide more headroom and sound ease when it reaches 100db, but the reverse is the true, the class A 100 watt seems to provide more headroom.
I have tried to use another set of speakers which is much easier to drive and it reaches the same conclusion.
Can someone explain why?
Quality or quantity of watt, how do we determined?
samnetw
georgehifi's avatar
georgehifi
4,966 posts
 
A Class A single ended amp gets rid of whatever crossover distortion might exist in push pull circuits so there’s that, and when exposed to this phenomena the listener is rendered a better person almost instantly.
+1 for that, and that’s any class-a not just SE.
Ever listen to a pair of old ML-2’s in good working condition through good ESL’s with maybe dynamic bass like Monoliths, MAJESTIC!!!!!! So long as you don’t want party levels.
This amp keeps doubling down to 1ohm, I’ve seen it do it on the bench.
Cheers George
inna
5,245 posts
 
ML is in the past, Gryphon is in the present. Bloody expensive stuff, though.
kosst_amojan
2,095 posts
 
Eh... The drawback of SE class A is you don't enjoy the benefits of distortion cancellation without feedback or lesser feedback unless you use truly exemplary gain devices. The class A envelope also ends up being the hard limit of the amp regardless of power supply because the topology transitions into class B operation instead of AB. That's why I assumed the OP was referring to push-pull topologies. 
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