Mark V - odd noise

I've been through my share of odd noises from squeals to flub - but I got a new one that just started.

I've eliminated cables (both speaker and instrument), power sources, cabinets. Happening with 2 different guitars. The head was retubed with SPAX7's and EL34's, but I'm getting the noise with both 6l6's and EL34's.

Here is a link to a sound clip:

http://bestringtones.net/tim-kiem.html?key=noise


I'm palm muting the notes and lightly hitting the strings cause it makes it more pronounced, but it's noticeable with regular playing (just not as much).

Any ideas?

hI vickywin,

your link is a ringtones page... Not sure what I should listen to.

What Two notes product are you using?

We have a Mark V in our demo room so we can check.