I was looking at getting CMT 340's l/f/c plus a pair of CMB 170 and 2 LVr-12 subs.

For what that cost I can get 3 Sierra 2's.
The potential problem I see is that I only have a PB-2000 sub.
The PB 2000 is not a bad sub but I bought this with no experience in audio equipment.
My room is 20 x 25 with 8 foot ceilings.

This is a large room I was able to make the sub work fine with the Andrew Jones speakers but if I upgrade to the Sierra 2 's I am afraid that I wont be able to get the crossover point that I need to run book shelf's.

I don't want base that shakes the windows or rattle my teeth I just want to be sure if I go with the Sierra 2 's instead of the 340's that the sierra 2 will not suffer in sound quality or make not have the base I need to make them sound like they should.

If i need a better sub then I will have to stick with the 340's and the two LVR 12's the cost of the Sierra 2 's leave me no room to buy a sub at the same time.
Maybe next year my bonus will let me get a FV15hp but just can not do it at the same time.
I could get a mini dsp to make the curve on the PB-2000 the best it can get though I already have the mike for it