Hello all, I am looking for advice on my upcoming equipment change. I have the AV123 focus Line source LS9's due to land shortly. I currently own a Sunfire TGA7400 amp and dual SVS PB13ultra's. I am looking to make a change to either the amp or the subs as I can't afford to do both. I want to change to whichever will make the biggest difference in my system. The subwoofer change would be to the Seaton Terraform XL which Mark Seaton said would mate very nicely with the soon to arrive LS9's. The amplifier change would be to quantity three (3) Emotiva XPA-1 monoblocks for left, center and right channels and an older Rotel RB-980BX amp (temporarily) for the surrounds as it is only 120W per channel, until I can afford the XPA-2 for the surrounds. Which would make the more significant difference? Please HELP thank you!