I also depends on the cabs that you have hooked up.No, I don't think so, not for any useful length of time. It would take a heck of a lot more than just another output jack to make the 800 combos stable at 2.0 ohms! The combos do NOT have all the same guts as the 800 head. Maybe the same pre-amps (except the Stage), but definitely not the same power amps and outputs.
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I can't find it right now but, I once read agedhorse list several differences, all requiring very high quality components, that are involved between 2.67 ohm and stable 2.0 ohm amps. The only one I could think of was heat management, but he said that was way down the list. There's a reason why the 800 combo costs only $100 more than the 800 head. You don't get two neo speakers and a tuned cab for just $100. There's probably at least another couple hundred to get the head's stable 2.0 ohm power. Like even just the Impedance switches are different; both go from 8/4 ohm total, but one goes to 2.67 and the other goes to 2.0! Apparently it's a much bigger difference than the numbers make it look.![]()
There is a complex circuit involved when driving most loudspeakers and the ratings are almost all approximations.
A driver's impedance will change with frequency as well as how hard they are working (impacted by heat).
Some cabinets are rated for 8 or 4 Ohms while their minimum impedance might be very low.
Put 3 or 4 cabs in parallel that have a low minimum impedance and it's a much more difficult load for most amplifiers.