Quad57's and Janis W3 Subwoofer

I don't know the Quad57s but I have a W3 system that I use with Merlin VSM-Ms and it sounds great. I also have a W1 system that I use with Tannoy System 8 studio monitors that are fairly efficient (92dB/w) and quite fast. Integration has never been a problem. Proper placement, volume, and phase settings are important.

I used W1s and ESL 57s for years with good results - that's what they were designed around. Most people turn them up too much - it's easy to make them sound slow. The Entecs are good too for much $$$$.

Try to find some Scientific Fidelity Substrate woofers, these are the only ones I have heard that are fast enough to keep up if you have the amp to drive them. Good luck...