I was practicing at low levels last night with a new/old cab and the speaker was farting. The speaker is in good shape and is a decent brand/model (Eminence USA) so I am assuming the speaker is not the problem. I thought, obviously there may be an issue with the levels of my cab, bass and effects, but being fairly new to bass I found myself not knowing what to adjust or where to start. After some adjustments I managed to quell the farting but I am am still unsure whether I have my levels set correctly. I find that coming from guitar where I could easily tell what was pre and post gain or volume.. I can't with bass because it all sounds relatively similar to my ears. This is my current setup Active bass -> Boss GT-6B (thru fx loop) -> GK 400RB (1st series) -> Sovtek (laney clone) 1x15" cab My main questions are... 1. What is a good place to start on the amp in terms volume for the pre-, master and boost levels? (the GK400RB has a boost knob) 2. What level should my effects to be set to? The Boss GT-6 has a line level knob, master level (0-120) and each effect has it's own level (0-100). I noticed the farting was happening when the line level knob was almost full up 80%?, and the master level was above 60, and the effect (compressor in this case) was above 50. I did drop the levels to 60 and 50 and I think the farting lessened - but I'm not sure I adjusted the line level knob. 3. What level should my active bass EQ be set to? And what is unreasonable in terms of a boosted EQ? I think the farting was happening when the bass was boosted on the active EQ circuit. 4. If someone can also answer this, specifically to the GK400RB (series I), is it alright to use a voicing filter and the active EQ at the same time, or should you use one or the other? My 15" box is a bit midrangey (rear ported, large cab), so I am trying to cut some of those mids out. I guess in short, what I am asking, what should I set my levels to, and if set correctly, how do I know whether the amp is "handling" the signal I'm sending it. Other than farting, what are the tell tale signs?