I've got a TNT150 that I purchased new back in the late 80's. One feature that has been of particular interest to me lately is the variable crossover with high and low output jacks. Am I correct in assuming that the low output would be for running to seperate amplifier and the high output would be used for running an extension cabinet( 2 x 10" for example) without a second power amp? Would using a 4 ohm extension cabinet from the high crossover output provide any extra wattage or gain from the amp or how does that work? This amp has not seen much use lately but has been a real workhorse over the years. I've always thought it did pretty well as a standalone, but sometimes wish I had the clarity and punchyness that comes with running 10" drivers. Also, when playing with a full band I remember sometimes wishing I had just a bit more headroom. Perhaps running a 10" extension would give the added headroom or even just the perceived loudness I am looking for? I've also got GK 400RB from the same era that could could be used in tandem with the TNT or even by itself if I was to get a 4 ohm cab. Neither amp is super powerfull but I'm wondering if together I might have something? Although, I let a buddy use my GK 400 right after his Boogie head died to power his 6 x 10 Goliath(4 ohm) and he said he had plenty of sound.... and that was in a 4000-5000 capacity venue. Needless to say, he replaced the Boogie with a 800RB soon after.