just wondering what I should consider for my next sub.
currently have the hsu vtf mk2.

What are your goals? To have a 2nd sub, or replace the MK2 completely? Music? Movies?

Just a few more details, and some advice will start flowing.

No details needed. get an ep800

I plan on selling the hsu.music is very important to me but I still would like to have decent output for movies.70 percent music.

What is the budget?

1200 canadian dollars

You didn't specify whether you now have a VTF-3 MK2 or a VTF-2 MK2. Especially if it's the VTF-3, you might consider keeping it and getting a second sub as similar as possible to it. This would increase the net output available and probably more importantly, if properly placed would help smooth the bass response by minimizing the effect of room modes. The general suggestion from the research of Dr. Toole and others is placement at the mid-points of opposite side walls or front and back wall or in diagonally opposite corners.

For example, the Hsu VTF-1 could be added to the VTF-2 MK2, or the VTF-2 MK4 to the VTF-3 MK2. Your budget would of course also support some excellent single subs, such as the Axiom EP500 I use or the Hsu ULS-15.

Personally I find Axiom subs to better for music and do a very admirable job for movies. They have a certain richness/texture many other subs do not and it is this feel that IMO makes them more musical, YMMV.

Agreed Mr Wash! I now use my EP500 in my computer room for gaming and music. As excellent and powerful as the PB-13 is, I still sense as you do a unique rich musicality from this sub that is enjoyable.