I have dual subs from different brands also. Duals really helped flatten my response, and fix a few nulls, but nothing was 100%. It took time and frustration, but I've come out ahead.I would like to use dual subs in my dedicated theater. Right now I have a SVS 25-31 pc plus and I ordered a HSU vtf15 MK2. Can I use the SVS and the HSU in the room or would I need 2 X HSU VTF 15's?