@rooze
If your HSU subs lack continuously variable phase adjustment, then integration is more difficult. A simple method for integrating subs with mains is to disconnect one speaker and the sub residing closest to that speaker. At a medium volume, play a test tone at the frequency you've chosen for crossing from mains to subs. While you sit in your listening position, have a friend adjust the gain on the subwoofer amp until the output from sub and main is equal. At that point change the polarity on the main speaker putting it 180 out of phase with the sub. Again play the test tone and have the friend adjust the sub's phase control back and forth until you have maximum bass drop out, or a bass null if you will. Reconnect the main to it's correct polarity and the main and sub will be in phase. Do the same for the other channel. I use that method in conjunction with Dirac Live and it works beautifully.
If your HSU subs lack continuously variable phase adjustment, then integration is more difficult. A simple method for integrating subs with mains is to disconnect one speaker and the sub residing closest to that speaker. At a medium volume, play a test tone at the frequency you've chosen for crossing from mains to subs. While you sit in your listening position, have a friend adjust the gain on the subwoofer amp until the output from sub and main is equal. At that point change the polarity on the main speaker putting it 180 out of phase with the sub. Again play the test tone and have the friend adjust the sub's phase control back and forth until you have maximum bass drop out, or a bass null if you will. Reconnect the main to it's correct polarity and the main and sub will be in phase. Do the same for the other channel. I use that method in conjunction with Dirac Live and it works beautifully.