I hadn't used my Variax 500 for a month or two so I put new Duracell AA batteries in it and plugged it into my Focusrite Solo USB interface the same as normal, but I noticed that I now have background hiss that I never noticed before. Has anyone else had this issue and know what the cause is? I tried a different set of batteries, connecting via 1/4" jack on the Focusrite, going via a DI box into the XLR on the Focusrite but it still has the hiss. Do you think using an XPS would fix this issue or potentially make it worse? The hiss is the same no matter what model I am using so I don't think it is related to the model's gain settings. I have also tried with multiple cables and the result is the same. Does it sound the the Variax is starting to fail?