Hello Mdrew,
Hope you are well. The people at HK were not thinking very well. You can use the channel 7 and 8 pre-outs to the sub. Hook them up to the left and right line level inputs. Plus you can just switch the cable pre-outs to change to the HT when you do home theater, so one sub for both zones, big benefit. Could use an a/b switch box.
If you are willing to put a cylinder sub upstairs, in the $700 range I would try the SVS 25-31PC Plus for $775. If you are going with a box sub I would see if you could stretch your budget to the SVS PB2-ISD at $899, $199 over budget, but your room is very large which is difficult for a subwoofer to pressurize.
Of the subs you mentioned, either the VTF-3 Mk2, or the SVS PB1-ISD are very good subs. So, toss up between them.
Keeping in the price range take a look at the SVS 20-39PCi at $599 since you can now place it upstairs again. I tried this on my Harman Kardon AVR 630, to make sure the channel 7 and 8 pre-outs work along with the speaker cable outs to a set of speakers, works fine and dandy.
Enjoy whatever you decide to buy.
Later,
TonyM
