How to setup gx-10 with my 5150 iii 50S effects loop

[luck1001]

Is it possible to hook up the boss gx-10 to an effects loop on my amp? I've tried the 4 cable method but the effects come before the preamp on the amp which sounds horrible when using distortion and delay

[luck1001]

If this unit doesn't work with a heads effects loop, why not state that? Now I have to go return it and I won't be buying another boss unit.