I picked up a SMSL SD793-II DAC/Amp (https://www.amazon.com/SMSL-SD793-II-PCM1793-DIR9001-Amplifier/dp/B00A2QLPJM) last week and have been getting static issues. My audio source is my PC via optical and it is powered with an AC adapter. Even with the optical cable unplugged, there is static so I...