Quad57's and Janis W3 Subwoofer

I have a pair of Quad57's. ** I have a chance to purchase a Janis Bass System to compliment the Quads. Includes W3 subwoofer and Interphase 1A System Crossover amp. Would this work?

System: EAR 834 tube integrated, Cary 301 tube cd.
*** Any input would be appreciated.

A industry insider (manufacturer of high-end limited production cables) once informed me that Janis subs really suck--too slow to keep up with Quads. FWIW, he uses two Entec subs with his system.

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...