I'm sorry that you're having such difficulty.

The readings you mention are about right for measuring the DC resistance of loudspeakers made to have a 4 to 8 ohm nominal impedance for audio signals.

The only other thing I can think to suggest, and this may be tedious, is to run one speaker at a time with the exact same material for the same amount of time at the same volume level to see if driving a particular speaker causes much more heat than any other. Because your speakers do not appear to have identical impedance, I would expect there to be some variance from one speaker to the next, but if a particular one causes the cut-out when no others do, I would tend to suspect something about that speaker. If 2 or 3 of your speakers, one at a time, cause cutout, I would tend to suspect the amp.

In any case, if your amp was recently purchased and proves to be defective in some way, Outlaw is likely to exchange it for another one. Especially if you are still within the first 30-days, I recommend that you contact Outlaw immediately.