When installed in my truck, (as it is currently) my 2500D has an Eclipse 5v deck + an Audio Control Overdrive feeding it signal. The overdrive is set down pretty far, but I have my eclipse sub out near full signal. So I think its a thing of not like 8 or 10+ volts, you will be fine on 4v, not to mention it will be very short bursts that your deck would be sending out that level of signal, so you will be fine in that respect. My only mark against, and its not really a negative thing, is that the gains seem to be very touchy on the 2500D. Nick, has had the same issue, but just be smart with it and that amp will do you right. I have run it as low as .5 and at the moment it is running at 8ohms and doing great.