2 ohm speaker off HU?
If you push the setup really hard for a couple hours and don't see problems... it might be and just result in some long term degredation.
I think it's quite possible the h/u will shut down after a good amount of bass and loud playing.
You might want to try it out while the dash is still apart - and feel for how hot the h/u gets with this setup.
g/l



