I had an old Dell laptop where I could "hear" an external USB hard drive spinning up in my headphones, but only if it was connected to a USB port on the same side of the laptop as the audio jack.
Dell is terrible about this; On my last 2 workstations I could hear my mouse moving if I plugged my mouse into the USB port next to the headphone jack.
UGh. Reminds me of the terrible USB powered speaker bar for an HP LCD I have at work. The audio comes from the 3.5 mm jack and power from USB. All you hear is the damn switching noise from the motherboard. Any time there is significant CPU use you get this noise in the background and it's quite audible at even moderate volumes.
Not sure if it's the crap speaker bar; power and audio coming from the same chassis using two different cables or the motherboard. Could be a ground loop? Now That I think of it, I'll try to power the USB from a lab supply or beefy USB charger.
Did you buy it from the guy who took his battery powered Dell with him as he sailed from California to Hawaii? 1000 miles from land, he could still hear the 60 Hz. hum.
