Fender flats sound funny - worn out?

[kipsus]

I have a mix currently, ADG strings from a new fender stainless flats light set and E from my old (bout 1 year) ML set because I found the E from light set to be too twangy and too loose.

Now what I have noticed is that the old E sounds kinda mushy compared to the new ones. There's plenty of fundamental and the tone is nice and growly but when I tried tuning with harmonics (usually use a tuner) the sound almost immediately fades away. and it doesn't just get weaker, it morphs into a mess of sounds, like an uncontrolled mwah.

The question is, can it be the string itself or maybe a worn-out nut or something?

[Pilgrim]

It's probably just the difference in the strings because of age and type. If you didn't hear it at first, it was because the ADG strings hadn't settled in yet.

You have the right idea in using flats for a long time. old flats sound great. However, I think you'll do better with a matching set on all strings. I like the Labella Deep Talkin' flats for a classic sound, and I find they last a looooooooong time.