I recommend you start by setting to small with a cross-over of 80Hz in the receiver. You can then tweak from there. I have my 80s set to 80Hz for movies and 60Hz for most music. And if you have a direct vs. stereo mode in your pre/pro, direct sends the bass to your 60s as well whereas stereo does not. So you can experiment with that too.
Along with my 600, I presently have the STF-3 until tomorrow morning. I've noticed that I can get the Hsu to sound much tighter when I set the cross-over to the same setting as the receiver (which is actually very surprising to me). So you can also experiment with that.
