Hi There,
Since 2011 I use of 10 Line-6 XD-V70L systems for a music theatre group.
I combine the body packs with lavs fron Microphone Madness lollipop well as Sennheiser MKE-2's. However, from the very first beginning the signal is polluted with a very high pitched whine, especially when the belt pack is not in direct contact with the skin of the actor.
We avoid the problem by wearing the packs close to the body, but in two topics I read about a whining noise which might be the same as mine:
http://line6.com/support/topic/8372-xd-v75-distortion-again/
http://line6.com/support/topic/7389-input-impedance-tbp12-beltpack-when-pin-4-tied-to-pin-3/?hl=whine&do=findComment&comment=53250
Do you expect the problem to disappear when shorting pin 4 and 3, of is there an other known issue with these (slightly aged) packs?
Best regards,
Daan Hoffmans