Can I apologise in advance if this is something which has been covered in previous threads but I have been unable to find anything appropriate using the Search facility. My signal chain, via my pedalboard, currently is: Goodfellow GBIV Active Bass > Boss TU2 > Boss GEB7 > Boss DD3 > SABDDI > Ashdown Combo. All cables checked and OK. Power Supply from 2.1 amp AC/DC adaptor. My problem is that, if I take a lead from the 1/4" Effected Output of the SABDDI into the Input of my amp, I get a horrendous hum both through the amp and PA (when direct injected). If, however, I put my board throught the Effects Loop, everything is totally silent with no hum at all. Any ideas? I know that the obvious answer is "Just put it through your effects loop then", but it is really bugging me. As always, all help and info gratefully received.