It really depends on your preference for music or HT.
For around 600, a good combo sub for both is the Velodyne
f1200x or the spl 800. The Velodyne ULD series although older are great subs and very musical if you just want to add a sub for 2 channel. Again, I am partial to Velodyne due to the price/performance... Others to consider are
Sunfire... gets very nice reviews and possibly REL.
Best of luck,
Joe
Custom Audio LLC
For around 600, a good combo sub for both is the Velodyne
f1200x or the spl 800. The Velodyne ULD series although older are great subs and very musical if you just want to add a sub for 2 channel. Again, I am partial to Velodyne due to the price/performance... Others to consider are
Sunfire... gets very nice reviews and possibly REL.
Best of luck,
Joe
Custom Audio LLC