Audio Output Functioning As An Input And Signal Coming From An Unplugged Amp

[BigBubbaBrown]

I have my DX7 controlling my Optimus (basically a Casio branded for Radio Shack if you've never heard of them, not sure they sell them anymore) and both of them running to a guitar amp.

Since I have my keyboards set up next to my computer I had to put my amp pretty close to it, which was causing interference so I turned the amp off, unplugged it, and plugged my headphones into the front of the DX7. Then I noticed that the audio from my Optimus was going through the DX7.

I eventually figured out that even though the amp was turned off and unplugged that it was still looping the audio output from the Optimus into the DX7. It would make sense if the amp was on but it wasn't even plugged in so I'm not sure what's going on there. Then I routed the output from the Optimus to the output of the DX7 with the same results.

I remember when I was younger that my brother use to play a joke on me where he'd take a portable black and white TV, turn the brightness all the way down so it looked like it was off, then run the headphone output into the headphone output of a portable radio to try to convince me that they turned The Price Is Right into a radio program so I was already aware of the effect. I was just wondering if it would cause any damage to the equipment, though.

It seems like a very handy feature since I wouldn't have to worry about digging up old cables to run both keyboards into my sound card but if it can short out my system I need to know so I can avoid it. And if it is harmful how do I prevent it when I run both keyboards to the amp or sound card?

[john]

Hi

I wouldn't think it would cause a problem, or it already would have. The main issue I can see would be that of separation, given that your puter is a more viable editor and mixer. ie if they are already being summed into one output, it might be convenient for quick playing about, but when it comes to recording it cuts down on your mixing and production options by having them in the same stereo pair track.

What I would do:

Work out how to have the inputs of each instrument come into your PC and monitor your PC output (assuming your overall system lag doesn't cause issues), some sound cards do offer monitoring of the inputs to your computer bypassing loads of processing.

There is a possibility that your amp has a switch to control this "straight-through" behaviour. The whole point is to know why things are happening, so you can make them easily not happen when needed.