60D external mic input - using other audio sources?

I was at a show the other night, recording a buddy's performance with the video model of the 60D. To try to eliminate ambient noise, I used a RCA-to-mini-jack cable to tap into his amp's Tape Out output instead of using a boom-style external mic.

Even with his line output dialed down to the lowest setting, and the input on the camera set to manual and the lowest level, the audio was really, really hot when I played back the videos later - distorted almost to the point of being unusable.

The manual says that I should not plug in anything other than a mic, but I'm hoping there's a workaround. Any help?

You need to buy a cable with a built -25db attenuator. The MIC input expects a low level input, while the Out output on the amp is giving a high output signal, thus creating the distortion. Sam Mallery gives an explanation on the details

http://www.sam-mallery.com/archives/8​92

dp

Thanks, David. That makes sense. I'll pick up that cable before the next show.

I need to be prepared for some other audio possibilities also: right now I can tap into RCA outputs, but don't have anything for XLR or 1/4" outputs. I suppose I'll cobble together a variety of options which will accept the male plug of that attenuator cable, and whatever source output happens to be available where I'm recording.