KT 66 push pull vs 300B single end

Thanks very much for your detailed description. It clarifies quite a lot for me and tells me  I am headed in the right direction for my low volume listening levels. 

Since starting this thread I have comited to the purchase of a pair of AN P4 mono blocks to go with my Tannoy 12" MG's. The MG's are a 92.5 efficiency rating.
I have a nice little Sunfire Jr I may round out the bottom end with if needed. 

Thanks again

Yes.
Push-pull amps, especially those that have a dedicated 'phase splitter' circuit, tend to make slightly higher distortion below a certain low level power. Usually this is about 5-7% of full power.


Single ended amps tend to have distortion that decreases linearly to unmeasurable as power is decreased.


So if you are playing both amps on a speaker that works well for the 300b amp, the 300b amp will appear to be smoother and more detailed. If the speaker is less efficient then things will go in favor of the push pull amp.


As SETs are built with greater power levels, the bandwidth suffers- 7 watts (300b) is about as big as an SET can get before power bandwidth really starts to be an issue (usually bass response is curtailed)! On top of that if you really want to hear what the SET is really about, its best to have it on a speaker that never needs more than 20% of the full output power of the amp. This prevents higher ordered harmonic distortion from showing up (when it does, it contributes to brightness and harshness while also seeming to be more 'dynamic' due to how the ear perceives distortion).


If you use a subwoofer, its a bit easier to get around this latter problem- most high efficiency loudspeakers aren't very good about making bass.