I use a Boss TU-3 tuner along w/ my GLXD16. I use it for powering my other few pedals & so I have both silent and unmuted tuning option.I'm wondering why you have a polytune2 on your board when you have a Shure GLXD16 (which has an onboard tuner)?
The reason I'm questioning is because I've noticed some discrepancies between my Shure GLXD16 and my Sonic Research ST-200.
