Okay ... the Quads are back ...
Despite their (only) slight lack of bass, the Quad 11L2s are so much more clear than the Infinity RS4001s. To use a hackneyed phrase from the hifi press, it's as though a veil has been lifted.
Besides, they're not that short in the bass department anyway. I really think I'd like to try them with a sympathetic sub. In the UK I was using Mission 76s - I think. These worked seamlessly with the IPL sub kit.
Anyway, it looks as if this is converging on a typically European setup - stand speakers, modest amplifier, definitive audio source. Frowned on the US, I know, but listen to it ... just a bit more tweaking ...
The back of the speakers shows the weedy speaker cable and rather more beefy speaker jumper cables ... I think I'll work on this aspect next.