Counterpoint SA-3000 Preamplifer


My preamplifier now has a his that I don't know where it's coming from.  Does anyone know what might cause this issue.  
Also does the tubes need to be biased? if so, does anyone know how to do it?

Thanks
chan-audio
if it is in both channels, it is power supply related... if it is in one channel it’s a tube, resistor, or capacitor.
Counterpoint has a great reputation. Amazing gear. Get her upgraded, , replace caps / tubes. Enjoy another 20 years!

great stuff!
Thank you all for your suggestions.
I've hired a electronics' repair company to evaluate my SA-3000.  I'll let you know of his findings.