Do I esentially have a class A amp?

Runnin, 250W would be nice if you can get it for the same price as 100W but if it is more money than perhaps getting better 100W (better design, better components) would bring more satisfying sound.

Bifwynne, Local feedbacks are better. Even emitter (or cathode) resistor is a form of NFB. SS amplifier, being voltage source, needs feedback at least for the output stage. Tube amps, being power source, most likely need less of it.

It is possible to design amplifier with negative feedback free of TIM. Since problem of TIM is caused by summing fed back delayed signal, during fast transition, it would be logical to prevent fast transitions and to eliminate delay. It comes to bandwidth limiting input stage before summing point and extremely fast output stage. High quality parts have to be used to achieve good initial linearity and wide bandwidth. NFB should be mostly local but also shallow just to bring THD distortions to about 0.5%. Bandwidth should be limited at the input to one that amp had before feedback was applied (since NFB widened bandwidth).

Such amp will have 0.5% THD and perhaps only 50kHz bandwitdh not to mention relatively high output impedance. THD distortion is not that audible, 50kHz bandwidth is passable and output impedance doesn't matter because inductor in series with the woofer is about 0.1 ohm (limitting DF to 80) while speaker impedance (being source impedance for back EMF) is mostly resistive.

Would you buy 100W amp with THD=0.5%, 20-50kHz, DF=50 when somebody else is selling 250W with THD=0.01%, 20-200kHz, DF=1000 ?
Specifications are useless - only sound matters. All comes to good design, quality (expensive) components and smart compromise.

Kijanki, Could you translate the paragraph you wrote into English please, particularly the phrases framed with double astericks (**):

"Such amp will have 0.5% THD and perhaps only 50kHz bandwitdh not to mention **relatively high output impedance.** THD distortion is not that audible, 50kHz bandwidth is passable and **output impedance doesn't matter because inductor in series with the woofer is about 0.1 ohm (limitting DF to 80) while speaker impedance (being source impedance for back EMF) is mostly resistive.**

Thanks

NFB lowers output impedance. If amp has 10x higher gain before applying of NFB then feedback will lower output impedance tenfold. We call it 20dB feedback. As a result deep NFB some amplifiers end up with output impedance of single milliohms. There is no need for that, since inductor in series with the woofer is about 0.1 ohm, while the fact that speaker's internal impedance is mostly resistive limits even more. When speaker's coil moves in response to signal it also generates response (back EMF) that works like brake that limits coil movement. This brake has damping effect on the membrane.

DF=1000 looks good on paper but it doesn't make big sound difference. Deep NFB used to achieve it, on the other hand does, making sound bright and unpleasant. Highly praised Atmasphere amps have output impedance in high ohms (DF=1).
Some speakers work well with low output impedance amps while others, (overdamped) sound great with tubes, but sane level of DF is perhaps 100.

It is very tempting to improve specifications with NFB because it doesn't cost anything. If you see fantastic spects in cheap amp you know that something has to give - it is sound.

Kijanki,
Bravo! What you wrote has been confirmed by many who simply use their
ears. Those supposedly impressive specifications made possible with
increasing NFB don't result in high quality sound IMO.

Charles1dad, Thank you. Atmasphere mentioned negative effects of NFB many times. I still believe that shallow NFB can be used but design has to start with good circuit and quality components. The best is perhaps not to even think of it and just to listen.