for 600 i recommend 2 orions 12's from ebay or go 1 12" x.x.x thats 405 i believe, or 1 12" brahma around 400 i believe. for the x.x.x reaudio.com for the brahma adireaudio.com, for the orion ebay.com, though i believe all of the subs i listed are found on ebay.