This has been an ongoing issue. Everytime I get a new pair of strings, they sound fine and punchy. But after a while the E string just sounds dull and flat, even when the others are still bright sounding. This has happened with Rotosounds, TI flats, and D'Addario roundwounds (happened only after a week on the D'addarios) Is there any way to prevent this? I've tried cleaning the strings after everytime I play, and washing my hands before playing. But everytime its just the E string that sounds dead, none of the others.