Originally Posted by johkarmau
I installed a MC-HD-AK4 (amp/harness/4 speakers) in my 2011 HD Roadlide w/factory radio and everything worked great. The distortion started after I installed a BTA6100 powered tube and harness FAST-HD-SIK. If I unplug the fast harness from the amp it goes away. Also, the engine has to be running before it distorts. Anybody got a suggestion?
Sounds like a ground issue. Verify your current ground connection with a DMM. Change the location if necessary.