You are correct it seems I hadn't punched the station cable to the block hard enough, once I got past that, the 6 foot cable causes snap crackle pop on the stations attached to the expansion cabinet.

They have an in house cabling genius who is going to see about getting one put together...

Hunting down a spare XTSc-IP cabinet with a couple cards this week and will swap back (because the 4 box solution is functional if I can get the cable the right length... but not quite as clean.

Now to find a newer main processor the the XTS that been buried in my garage for some years....