I've used Massive Core-1 in my own vehicle since the first shipment got sent out last July, 2015. Full disclosure, here are the issues I've had.
1) The first unit I received mysteriously stopped connecting to a PC. Nothing could resolve it. Massive Audio accepted a return and I got an entire new unit with all the accessories as a replacement. This has not happened even 1 time with the replacement unit. I could not ask for more from Massive in terms of customer service.
2) A few times, maybe 5-7 total, the unit has powered on yet when starting the car yet it will not pass audio. The solution is to unplug the power connector, which does not have to be done with the vehicle switched off, and reconnect the power.
3) I almost forgot this but it has happened more than one time. The bass will not play until the remote volume knob is adjusted. I have the remote knob programmed to control the output level of the subwoofer channel only.
99% of the time the unit functions perfectly. I don't even think about it. I do offer this DSP for sale if you're looking to buy.