Since the topic of a high pass filter has been mentioned I figured I’d share this, as it may be of interest to some - particularly Ayre Acoustics owners. I own an Ayre VX-5 Twenty amp. For that amp, and a few other Ayre units, a replacement "high pass input board" is available. Ayre makes a tweak to capacitors on the board to provide a high pass at 100Hz at the amplifier input. So the amp can feed the mains at 100Hz high pass, and the other output on my Ayre KX-5 Twenty preamp can feed a pair of subs. Evidently it’s common for Vandersteen owners using Ayre equipment. I’m getting to know a pair of Wilson Audio Duette with a pair of subs and I have a pair of these boards. I haven’t used them yet, but I expect they will be very handy - especially since I very much like 2-way speakers paired with subs to dial in the low end. I should be able to play with any 2 way speaker and should get a nice benefit from taking stress off the amp, and the woofer of the 2-way. The fact of the matter is, the Wilson Duette sound so good without the high pass filters I haven’t been in a rush to install them!