I've played through amp heads with BAss, lo mid hi mid, treble eq. And while playing live i never got a good punchy tone out of it. I never knew how to dial them. On three band eq amps i just max out the mids and dial the bass and treble eq til it's a good tone for me. I wanted to know how i can do that with the lo and hi mids on bass heads that may have the 4 band eq - bass, lo, hi, treble.