I need the most clean lows I can get at 4 ohms - with f E A R f u l cabinets (the TB spell check had me typing "tearful" - what the heck?). I've got TFB-550b right now which is as we know, excellent. I'm curious if a TFB-800b2 would give me more clean low end. Do any of you have direct experience with both of these heads ? Thanks.