I haven't taken them apart, but I did look in and there is a ton of room in the case. Funny enough the amp boards are actually mounted upside down and attached to the top cover. Since this guy has a legit warranty, I will avoid opening or poking around unless they tell me otherwise.
Re: the 'short' test - the manual does state that the amp is short circuit protected via DC short protection. From the manual:
"In the event of abnormal operating conditions, the IPR has built-in amplifier protection. Under conditions that would normally damage the power amplifier, the DC LED will illuminate and the amp will automatically attempt to restart to correct the condition."
Another point worth noting is the amp is circuit breaker protected, not fused like some other amps.
I won't be the first to intentionally test this feature,
but it's nice to know that that is built in and also backed by a (US) warranty.
Oh - for anyone potentially interested, there are 2 brand new units at regular price on ebay with free shipping right now.