A 9 watts beats Passlabs, EAR and YBA ?

Hi, Eldartford, the idea that you can run zero feedback at some audio frequencies and then use feedback at low frequencies suggests to me a gain non-linearity that changes with frequency. So that would take some tinkering to make that work, to say the least. To my knowledge no-one does this, as the idea behind many amps that use feedback is the concept of 'constant voltage' wherein the amp is capable of constant voltage regardless of the load impedance.

Zero feedback amps do not behave this way for the most part, usually subscribing to a different idea wherein the amp makes 'constant power' with respect to the load.

These two ideas have been in conflict in audio for the last 50-60 years, resulting in the tube/transistor debate and the subjectivist/objectivist debate, plus the general idea of component matching.

Robertwolfee, the Pass Labs amplifier is class A, but it is not tube. However it is one of the best-sounding transistor amplifiers out there. At any rate you will need some power for the Maggies, so due to the power limitations of most SETs, you won't get them to be very practical with your speakers although I am sure they they would sound fine, just at very low volume levels.

Atmasphere...True... if the feedback signal had gain increasing with frequency reduction the overall amp would exhibit LF roll off. But that would be easily corrected by equalization of the input signal.

But the causial relationship between propagation delay and odd harmonic distortion still eludes me.

Eldartford, you mean, 'How come the propagation delay in an amplifier causes odd-ordered enhancement and not even ordered?'

To answer this I think you have to look at the components of a square wave -odd ordered harmonics- and then look at what happens when you add a delayed inverted signal to the original signal. The result has a bit in common with what happens to a sine wave when you start adding odd-orders to it- it makes the resulting waveform wider on top and bottom, without changing the frequency. I think the only way you can interpret that is 'odd orders are enhanced'. My take on it anyway...

Atmasphere...Thanks. I still don't get it, but am willing to believe you are correct in your conclusion. Until I run a little simulation anyway :-)

Eldartford, I'd love to hear about your results!