Speakers: Boston Acoustic A40. The surrounding on the woofer's are rotted out so figured I need to replace them. On the cabinet it says that they are 8 ohm speakers. Here is the replacement woofer available: Receiver: TX-SR501. The specs say that it is an 8 ohm receiver but I am confused by the following: 3 ohm 160 W/Ch 4 ohm 125 W/Ch 8 ohm 85 W/Ch I read that in order to run a speaker with 4 ohm woofers you need a receiver with a minium impedance of 4ohm. I basically want the best sound from these speakers and would like them to work with this and future receivers that I purchase. My question is should I get the 4 or 8 ohm woofers? What do those receiver specs mean (I am running a cheap polk center, and small mirage rears, basic sub woofer). I read ohms everywhere and have no real concept of what they are or how to optimize the system. Thanks in advance for any insight.