I would like to know if my receiver is powerful enough or if I should run an amp for better sound quality. Marantz sr5003 Receiver Def Tech Mythos 2 Left and right Def Tech Mythos 3 center Martin Logan Helos 20 surrounds I am currently running a 5.1 system with a living room size of 20x20. If an amp is suggested what would be a good quality amp for a reasonable price as far as cost to value would go. Thanks Mike