Humming Jazz Bass 24

[Jaco D]

I have a year old Jazz Bass 24 with the standard Saymour Duncan Quarter Pounders. Lately, instead of using my amp, I've been using my Digitech BP200 as a headphone amp and a pair of headphones since I only get to practice after midnight before going to bed. Anyway, I've noticed that the bass is quiet, without a trace of hum or noise even when the volume and tone settings are at max. However, when I pluck a string at those max settings, I get a feint noise and hum that goes away when I dampen the strings and then take away my palms from the strings.

I'm not sure if this is expected of single coils or the SD QPs specifically, nor am I not sure if this noise/hum has always been there but only became obvious when I put on the headphones (it's not irritating really). I was thinking of putting shielding tape in the cavity (right now it just has black shielding paint). Don't know if that would help, specially if this is a grounding problem.

Thanks for any assist in advance.

[Jiggybass]

I have the Jazz 24 aswell, with the SD's.

I get the hum only when I plug in at certain parts of the house, so it could very well be a grounding problem.

OTOH, If you can't hear it without the headphones, then there's no reason to worry about it, maybe the headphone jack itself isn't all that great? who knows?

[202dy]

If the hum diminishes or disappears when you touch the strings it is normal hum. If the normal hum bothers you, leave your hands/fingers on the strings.