I hope you guys will take the time to read this reply in detail:
I just went through everything that has been discussed in the last half dozen or so replies........I received a defective NEO410 and emailed Dave with the complaint. He arrived at the conclusion, based on my description of the sound, that the crossover was probably defective and then told me he'd send a replacement for me to install. I wasn't thrilled at having to do the change out on a brand new piece, but considered it easiest for me, since I'd otherwise have to box up the cab and wait for DHL to pick it up, etc.
It came, I changed it out, and the problem persisted. That's when I sent an email to Dave letting him know that I wasn't happy - after all, if I had bought a new microwave on line and it didn't work, I wouldn't expect the seller to send me a part and ask me to install it!
Dave replied that he was very sorry and that my satisfaction was his main concern, and that he would change out the cab with a replacement and pay for return shipment of the original as well as shipment for the replacement. Although I didn't ask at the time, I am sure he would have changed out the original cab for a replacement if that was the option I asked for.
The defective one is on it's way back and the new one is on the way here, so I expect to be up and running soon. I expect that once the new cab is in service the problems will be a distant memory.