Yes, the OEM Black Knight speaker is rated at 8 ohms impedance, but the OEM game amp is based on a TDA2002 - which wouldn't have a problem running a 4 ohm impedance speaker. Check with the manufacturer of your aftermarket sound board for exact specifications, as it could be different.

IMO, You probably don't have a sound problem simply because of the impedance of the speaker alone....but try testing with an 8 ohm speaker. If you don't have one, surely you must know someone with a stereo system you could borrow one from.

You’re DMM won’t measure the impedance of a speaker. You’re measuring the DC resistance. All your meter will tell you is if a voice coil is shorted or blown open.

What’s the issue you’re having? If it sounds like poopy, you could have a speaker with rotted surround foam or a hole in the cone. I’ve seen speakers in pin cabs that are loose and really sound bad too.

Did it do this with the original sound board, or is this a new problem that cropped up with the aftermarket sound board?

I think your best bet is to exchange the Kohut if warrantied. At least that would rule it out if its the problem. Sounds like the temporary disconnection and reconnection is restarting its communication, for some reason it stops reading data sent to it. Just my guess.