My Epi LP seems to always be slightly out of tune most every time I pick it up...my LED tuner always shows it just a bit low on the Low E, A & G in particular; it's a little annoying.
Would changing the nut out from the stock one fix that?
If so, any suggestions on a good replacement brand?
Or if it's not the nut, can anyone give suggestions to fix this?
The guitar is an imperfect instrument and there are multiple ways to tune it.. And multiple things that can go wrong with the tuning.
First thing first, make sure the guitar has intonation set properly. Make sure the intonation is set to make the 10th fret and 22nd fret the same. (or 12th and 24th).
Now, when you tune up, tune using fretted notes on the 12th fret. The fretted notes should ALL be in tune on the neck, meaning, anything you play that is not an open string will sound in tune.
Now, tune using the open strings. When you play up the neck, do things start to get out of tune?
One of the little discussed things is that sometimes the nut is in the (slightly) wrong position. I received a new (cheap) guitar once where the nut needed to be moved. This was a difficult repair and involved filing the end of the fretboard and alot of trial and error. If after a professional setup, the guitar still does not sound in tune when using open strings, the nut may need some work.
Because the guitar is an imperfect instrument and there are multiple ways to tune it, most people tune around the limitations of the guitar. Which means some compromise. Its usually best to tune the guitar in the range where you will be playing, for instance, if you play alot of open chords, tune using the open strings. If you are a shredder, tune using the 12th fret notes.
Even on great guitars, there will be some perceptible areas that are out of tune around the nut. It depends on how the guitar is set up, how hard you fret, and how the guitar was tuned.
If you can't get it sorted, take it to a good tech. My bet is the intonation needs to be set and because its an inexpensive guitar, the nut might benefit from some work.