...Ok, stuck the Quad back and the differences are clear and interesting. The Topping has a rather warm and fat character that is very friendly, engaging, and really suits the Klipsch, though the closer one looks at it the more one begins to notice there's a slight lack of precision here and there and a hint of compression too - in comparison to the Quad the Topping sounds just a little blurred and out of focus, but in a really nice and attractive way. I could very happily live with it, but given the choice the Quad is the better amp. It's an interesting comparison as the traits I assign to the Topping are those one would assign to the 303 when compared to a more modern amp - the 303 can itself be viewed as being on the rather warm, rolled-off and soft sounding side of neutral (which is why I like it with Klipsch), I guess one could view the TP20 as going a stop or two further in the same direction.
I have a feeling that, if done properly, this A B dem would have split a room down the middle with many listeners preferring each amp, which for an item that costs £50 quid brand new is a hell of an achievement. I'll happily argue that a T-Amp and a pair of large and very efficient speakers is a perfectly viable way to spend a system budget! It really is that good!