DAC repair/troubleshooting in New England

I purchased a DAC in Taiwan quite a few years ago. It’s a dual TDA1541A, with a tube output stage. Really nice construction and components. Pictures are linked below. 
It’s always had a significant hum. I love this DAC and would really like to get rid of the hum, but not savvy enough troubleshoot myself. 
Anyone know a good place within reasonable driving distance from Central CT that would be capable of this?



Is there a usb input? Are you using it? If so, I will suggest something that may eliminate it. I am assuming you are referring to a hum through the speakers? The woofers? Like a ground loop 60 htz hummmmm.....
It does not have a USB input, just optical, coax and balanced. 
The hum does sound like a 60hz ground loop, or at least I think it does. 
Try just unplugging the input cable you are using with the unit on and off. Does the hum go away? 
Hum is definitely there with no inputs connected. I usually use the optical.