I'm hoping someone here can assist me in isolating a problem I'm experiencing when I connect my Yamaha Tyros keyboard to my Motion Sound KP-100S stereo amp via a Hosa 10 foot duo audio cable (with two 1/4" plugs (L/R) at each end).

Here's the problem - With the Hosa cable connected to both the Tyros & KP-100S and both units turned on:

If I jiggle around either of the Hosa's 1/4" plugs plugged into the KP-100S's 1/4" inputs, I hear an awful loud grating crackling noise come out of the KP-100S speaker(s). This annoying sound will also appear intermittently and unexpectantly even when I'm not touching or jiggling the jacks, and with the Tyros powered on, but with its volume knob set at the the minimum volume level (no sound) position.

If I unplug the Hosa cable from the KP-100S, yet leave the KP-100S turned on, the problem goes away completely.

Also, leaving the KP-100S power turned on, keeping the Hosa cable connected to both the Tyros keyboard and the KP-100S, but then turning off the Tyros power, makes the problem go away as well.

Based on the above, what do you guys suspect may be the 'source' of the problem: the Hosa Cable, the Tyros, or Motion Sound KP-100S?

My initial impression that there may be a bad connection (loose fit?) between the Hosa 1/4" plugs and the 1/4" inputs on the KP-100S.

Has anyone else here ever experienced anything like this? Feedback & help appreciated. Thanks.

Scott