Just unpacked a brand new unit and connected via xlr to a line 6 KB37 interface and all we get is bad hum and static with nothing coming through the mic (Shure SM7B). It seems like there is no signal at all. Mic works fine connected directly to the KB37. We also tried connecting the 12AY7 to a powered mixer via xlr and got the same result. I’m trying to find out if we are doing something wrong or if it’s a defective unit. I haven’t pulled the tubes or anything and we have a moderate amount of experience hooking gear up.

Thanks to anyone who may be able to help.