Originally Posted by Brandon Strader
Even if you used a different string (G for D) it shouldn't have sounded out of tune... odd, sure, but not out of tune. You need to make absolutely sure that all of the strings are properly tuned before recording. With a real tuner, a DAW's tuner, or a VST's built-in tuner (like Guitar Rig's tuner)... There are some other issues but the guitars being out of tune is straight up the most important issue with the mix, so best of luck! Buy some new strings if you need to!
the thing is, the string would detune every couple minutes since it was looser, so it could be the final one I used wasn't tuned soon enough. I'm gonna get my guitarist to borrow my extra strat and rerecord it. Also I'll check the effects I'm using on Guitar Rig and see if any of them have a pitch bend or detune.