ive gone 1/8 cable from my wireless to the mic input on the cam. the audio is distorted. switched to 2 channel audio for this. any idea why??

Most likely reason for "distortion": you used a mono plug in a stereo jack. Many wireless mike-receiver units have adapter cables to convert the output to a 1/8' (3.5mm) mini plug. The mic jack on the CX550 is stereo. Look at the tip that plugs into the camera: if it has one black ring, it is a mono cable. If it has two black rings, it is a stereo cable. You can get a converter plug at places like Radio Shack. You want a mono 1/8th mini to mini-stereo. This has the disadvantge of projecting out and being vulnerable to damage. Alternatively, if you bought one of the XLR adapters you were considering, just use that, pluging the mike into one of the channels and setting the mono-stereo switch to "mono" so that it will feed the signal to both channels.

If the wireless receiver's cable has a stereo plug, have you checked the connection to be sure that it was firmly seated in the camera's 1/8" mic jack? It is possible to plug it part way into the jack and that will give you some distorion. (I've done it when connecting an XLR adapter to my CX550.)

Not sure what you mean by "switched to 2 channel audio for this. any idea why?" Are you saying you got distortion even though you had switched from the CX550's surround sound mode to two channel? (If so, this was just information and not complaint). Or, were you saying you wanted to to record audio in the CX550s's surround sound mode but the camera will only let you record two channel stereo when you plug something into the mic jack? (That's what the camera does. When you plug something into a mike jack, you can only feed a stereo or mono signal.)