well, I've found my bass tone Holy Grail. I bought a used TFB420 a few weeks ago, a used Epifani T-112UL a couple of weeks ago and today I bought a brand new T-310UL (5.3 ohms). Holy S__t what tone! Best bass sound I've ever achieved. Playing my Metro RV-4 through the TFB420 & T112UL combo was great, so I thought about getting an 8 ohm 210UL to go with it when I needed more volume. Couldn't find one to try, but I found a new 5.3 ohm 310UL at Low Down Sound (great place, great guys). I started thinking about the impedances if I used both together. 5.3 and 8 in parallel works out to about 3.2 ohms. Not too bad. I figured the T-funk could handle it, especially since I usually don't play all that loud. Well, the 310 sounded great on it's own, I bought it and brought it home. The T-funk/310 combo sounded fantastic, so I added the 112 and it's even better than either cab on their own! Neither one stands out too much and they compliment each other really well. My guess is that the relative impedances and sensitivities makes the power/volume balance between the two just about perfect. The sound is punchier than the 112 alone and fuller than the 310 alone and still has great clarity and definition. The Thunderfunk didn't get overly warm at all, especially with the fan on. To be honest, I doubt that I'll need the output of both cabinets together very often, but it's nice to know they work well together if I ever do.