Hum in PC Audio Piped to Stereo System

[S***@19s8f37h9hj1jk2kl7f9r2Z.Com]

Hi,

I am having a problem with getting a hum in music played from my PC when
I connect the PC's audio output to my stereo system. I have tried
hooking up 2 different kinds of USB-based "audio cards" that take the
output from the USB into the external unit. Both external units have
stereo output jacks on them that I wire to the stereo audio in.

One of the units I've tried is the "SoundBlaster External USB Sound
System" and the other is the "Xitel MD Port AN-1". They both allow me
to play the music on the stereo, but they both add a hum which is quite
evident during quiet passages and somewhat audible even with some busier
passages.

Can anyone tell me about the causes of this problem and some possible
solutions (or point me to someplace that would have information on
this)?

Thanks in advance.

Sincerely,
Don

[j***@codemist.co.uk]

At what pitch? A 50Hz (UK) or 60Hz (USA) hum is caused by the mains,
and suggests that you have a mains loop somewhere. Something is not
properly earthed. If your hum is at a different pitch, no idea.
==John ff