TC, welcome. First, despite the size of your VR2s, you should set them "small" on your 320. They have fairly good bass on their own, but your KSW-12 is even better in the lowest bass and you should give it that responsibility by setting all speakers "small". Although your 320 gives you only 40Hz and 60Hz sub crossover choices when you set "large", with "small" you have 80Hz and 100Hz options and you should select 80Hz as the best compromise. The 60Hz setting you've been using is really a bit too low for the VP150; the frequencies under 85Hz aren't being totally lost, just rolled off from the sub, but the 60Hz setting does create a little weakness in that area and 80Hz will be better.
As far as the sub setting on the 320, when you set the VR2s "small" the setting is automatically "sub", which lets it handle the under 80Hz frequencies while all the speakers are rolled off below 80Hz by the 320. Turn the crossover control on the KSW-12 all the way up to the maximum frequency and leave it there to get it out of the way from interfering with the 80Hz crossover which the 320 is doing.
Yes, occasionally on movies the center channel does get low bass material under 85Hz, although dialog doesn't go lower than that. Good listening.
