The classic combination with ESLs since the 1950s has been ESLs and OTLs.
The impedance curve of the speaker is benign. The advantage that OTLs offer is that there is one less transformer in the signal chain so its more transparent. The other thing is that OTLs don't have any problem making bass on the speaker. In the bass region, the impedance of the speaker is so high that this is a problem for a lot of amps. This is why transistors don't do so well with them.
A minor correction: The Quad should not be driven by amps that make a lot of current, they prefer amps that make **power** (not just voltage). This means a tube amp, generally speaking. For more information about this see
http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php
The impedance curve of the speaker is benign. The advantage that OTLs offer is that there is one less transformer in the signal chain so its more transparent. The other thing is that OTLs don't have any problem making bass on the speaker. In the bass region, the impedance of the speaker is so high that this is a problem for a lot of amps. This is why transistors don't do so well with them.
A minor correction: The Quad should not be driven by amps that make a lot of current, they prefer amps that make **power** (not just voltage). This means a tube amp, generally speaking. For more information about this see
http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php