Love my 525 also. My friend's jaw dropped when he heard the STF-2 the other day(in town for the Christmas). He could not beleive how clean and deep it was, for $400. He even laughed before hearing it when I told them HSU got CompUSA to sell their subs. Then he ate crow after hearing it.
The best is when I told him i had the sub only at 50%. He asked me to turn it up, I did. No sounds of the woofer under stress, still ultra clean bass at an insane volume.
I'd keep the Axiom set up you have and get the STF-2 sub. That leaves you only a center channel away from a theater, something you say you will go to in the future. I do not see the need to send everything back, eat all the shipping costs, etc.
