I as well need to upgrade my sub. I have my new HT room built in a sound proof room in my basement with a 80's system and a ep175 sub. I also have a Sunfire jr in my living room. Of all the subs I hve heard nothing seems to compare to the Sunfire. Of course the problem is the cost of the things, I bought mine off a friend, used.
Still I wonder what a comparable Axiom sub would be? My 175 just does not seem to be clean enough? Could the setup be wrong?