Xfmr And Balanced Outputs?

[poneal]

I recently bought a professional amp from e-bay and I'm confused about speaker/xfmr outputs on the back of the amp. First what does xfmr do. Secondly, what does com stand for? They have different variations of speaker connections. I currently have the speakers hooked up in parallel and connected to the 4ohm and gnd connections of the amp. It works but im just curious what these other things mean and do. Any help or links to these would be appreciated. Thanks, Paul.

[FLZapped]

Usually you'll have a common, then a tap for the appropriate speaker impedance you want to use. So you should be conected from common to, in this case, 4 ohms.

-Bruce