Dual Overdrive Noise

[Adam_DIY]

I built a multi for my brother earlier this year with an eternity and a sho.  He's gigged it pretty heavily and loves both sides independently but gets excessive levels of noise when using both sides together.  He doesn't get the same noise when stacking the drive with an external booster or the sho with an external drive.  I'm assuming some shielded cable will help but I'm not sure which wires I should replace with shielded.  Any ideas?

[m-Kresol]

try using an audio probe to see where the noise starts. Input-boost input-boost output-drive input-drive output-output jack. once you know where it starts, try shielding one wire at a time until it's hopefully gone