Pass Labs XA30.5 and ModWright KWA150

What is the purpose of owning an OTL amp if you're adding an autoformer?

Because it might still sound great with an autoformer. For instance, it is still a Class A, triode amp. But I do agree with the general idea (not based on any technical knowledge at all)that there is some dissonance in the idea of using an autoformer when you have purposely decided on an OTL amp.

I agree with all of the statements about using an Autoformer (I don't use one and this is one of the reasons I went from M-60's to MA-1's) with Atma-Sphere amps.

When I ran tests with and without the Speltz Autoformer, I could always pick out when the Speltz Autoformer was being used. Anybody who tells you that it doesn't have a sonic signature is definitely fooling themselves - it is there.

However, Atma-Sphere amps + the Speltz Autoformer still sound better to my ear than most amps I have tried. The sonic penalty you pay for inserting the Speltz Autoformer isn't huge and is far less significant than the sonic improvement one gets by raising the impedance that the amp sees via the Speltz Autoformer.

George

OP, if tubes are out of the question for you, I would go with the Pass XA.5, it really does not get better than that if 30 Class A SS watts is enough to drive your speakers.