My current system is composed of a Yamaha RXV596 receiver with Axiom 1.5 mains (1988), Axiom AX 1.2 centre and Axiom QS4 rears. I would like to add a sub and am not sure what to go with. I found an AX 1.5 sub (triangular older design) which I could get for approx $300-$350 Canadian. Would this be an adequate sub for my system or would one of the newer ones (EP125 or EP175) be more appropriate. What differences are there with the newer design over the older triangular design. My room is approx. 12ft x 20ft and my seating is across the narrower (12ft) portion of the room from the system.

Also, I will eventually be going with either the M3Ti's or M22Ti's as my mains (haven't decided yet) once I have a bit more money. Thanks for any advice that would help me make my decision.