I have recently purchased a REDDI, and although I have been loving it I have started to notice a faint but noticiable buzz when I use the Thru input to an amplifier. I have an aguilar 410 cab and a markbass head. I have tried several different heads, cabs and power sources and it is still there. The only thing that I have not tried is switching out my power cable on my amp, which isn't the best but there is no buzz when im using just the amp and no REDDI. Or using a ground lift on both the REDDI and the amp. I was wondering if anybody had any ideas of what this may be. I'm trying to avoid sending this into the shop right because I am in the middle of a bunch of demo work but I am running out of ideas and it's starting to looking I will have to send it in.