Hi there, guys!

I've got a question for you, that I really hope you can and will answer for me.
Recently I've bought two guitars, both second hand, an Epiphone Les Paul Custom Black Back and a OLP MM1. On both guitars the low E & A string sound dull, almost as if they're being muted..
What causes such problem?
It's starting to annoy me a bit..

Could it have something to do with the nut being too dirty/tight on the strings??

Could be something as simple as old strings.

Could be a pickup is cranked up too close to the strings.

Could be your amp settings or the amp/speaker setup you're using.

The very FIRST thing I do with any new (to me) second hand guitar is clip off the strings, clean the guitar, polish the frets, check for level frets and put on a new set of Dean Markleys (Cold steel, blue steel, blue box whatever those are). They're fairly bright strings that will tell me whatever the guitar has going for it. I'll check the control cavity to see what pots are installed (there be idiots out there, maitey, who screw with the pots to produce "dark" guitars) and what other insidious things have been done the guitar by the mouth-breathers. And then I'll run it on a very clean setting with everything on the amp set to 12 and everything on the guitar dimed.