external speakers not compatible with laptop?

Hi guys. My wife bought a new HP laptop. We've hooked up Harmon Kardon's HK695 speaker system (two desktop speakers and a small sub), the same type I have on my PC. When it's running the speakers emit a low-frequency rumble, kinda sounds like audio on a video that's streaming. I tested these speakers on my system and have confirmed they're 100% fine.
Is there anything I'm doing wrong by having them on the laptop, or is there perhaps a step I'm missing? Thanks.

 

If it were XP I would say check out Control Panel, Sounds and Audio Devices, Volume tab, Speaker Settings, Advanced, and after that check settings under the Audio tab. Since it is a laptop I imagine you are using the outlet for headphones and a mini pin-stereo plug. Check connections by removing and replacing and try again. Rumble sounds like interference, possibly speaker placement, or a bad connection.

 

Hi TB2,

Sounds like a Digital speaker system connected to an Analog output. Just a guess!

Good Luck, Jim

 

The sub's powered, perhaps that's causing a problem?