So I guess I'm a victim of the fart syndrom as well then :-(
Have a great weekend Head Fi'ers
Hello Frank, we are mostly a generous crowd here. Welcome to the asylum. Do you have big ears?
If you are hearing harsh distortion with head motion or with adjusting the position of your 507's, you may be experiencing the "stax fart" phenomenon. Put that into the search function and see if that is it. I have found it to be more common with my 507's. It is an adaptable problem.
If it's not the Stax fart, it could also be a cable connection issue. Try if you can induce the distortion by gently moving the cable around while listening.
Furthermore, to rule out your source, try to swap the left and right channels at the inputs of your amp. If the distortion changes sides, it's your source. It's unlikely that it is, but it can't hurt to try.