I just purchased a KRK S8.4 subwoofer to use with my existing Audioengine A5+ speakers, connected to my PC via a USB DAC. The introduction of the subwoofer is causing noise issues and I'd appreciate some help in making sense of the current situation. All of my components are connected to a single power strip:
- PC is a custom build with a 750 W power supply using a 3-prong plug
- A5+ speakers have a built-in Class A/B amp (in the left one which powers the right) using a 2-prong plug
- S8.4 subwoofer has a built-in Class D amp using a 3-prong plug with a ground lift switch
- DAC is a small, relatively cheap NuForce uDAC-3 powered by USB
- Power strip is 3-pronged, connected directly to the wall
- My home is older and the electrical panel is probably due for an upgrade
- Without the subwoofer only a small static hum is emitted from the speakers at all times - barely noticeable, and definitely nothing to cry about
- With the subwoofer there is a very loud static hum from the speakers and computer noise leaks through as well - completely unbearable
- No combination of ground lift, polarity, or sensitivity switches on the subwoofer has any effect in lessening the noise
- I bought an iFi iDefender+ to use with the DAC which quieted the static noise right up, except...
- Anytime the DAC outputs sound, a loud whining noise goes with it until the DAC stops outputting. The noise is at a constant volume regardless of the DAC's volume control, and occurs at 1 kHz and all its multiples.
- When I use my laptop on battery as the input to the DAC there are no issues
- When my laptop is plugged into its 3-prong charger on the same power strip as the other components, I can hear the whine! It's not as loud as from my PC but still noticeable.
- When my laptop is plugged into its charger on a different wall outlet, there is substantial static noise in addition to the whine