Whenever I attempt to record sound form an audio cassette, there is a constant "buzz" in the leftt channel, which repeats at certain frequencies (6 kHz, 9 kHz, 12 kHz, 18 kHz, 21010 Hz, and so on), which is rather irritating.
It appears to be present at both sound cards I own (the nForce on-board and Sound Blaster 128), and with every cassette I try to record.
I reproduce the cassettes on my Onkyo TA-6211 deck.
Could anyone tell me what could be the problem and how to fix it?

Many thanks.

edit: Pretty please?

Some questions which could help to give an answer:

Is the buzz also present if you record from another source?
Are both computer AND cassette deck connected to ground?
Did you try another cable?

OK, they're connected to the ground and I tried about a dozen different cables.
When I attempt to record from a vinyl record player, the buzz isn't there.
Does that mean that the problem is in the cassette deck?

Will you make some recordings under different conditions and post the results?

Tape recorder paused
Tape recorder stopped
While recording to tape from another source
Tape recorder powered off
Tape recorder power cord unplugged

Where do I post the results?
And what kind of results - the wav files, or the screenshots?

have you tried a different tape deck?

of course, if the problem can't be fixed (or the tapes are no longer available as can often be the case with tapes so old that they can only be played once), you can easily just notch-filter out those frequencies and you'll never miss them.

Tx m8
that did seem to solve the prob... until the hardware fix
and I don't even seem to hear the quality loss, if any.