Windows Vista 64x, with integrated motherboard audio.

The output through my speakers has become very, very weak, even though all the connections appear fully functional when I test them withn both Realtek and Windows audio manager.

I have tried switching from 5.1 to stereo, etc., and played with the output settings, to no avail.

System volume is set at 75% as it has always been.

Audio output via my USB headset is unaffected and good as ever.

This is distressing me. I fear it may be a hardware issue and that I might have blown my speakers somehow. I do not over-stress them but they are Altec Lansings, about 6 years old.

Can anyone suggest a way to troubleshoot this, short of replacing all four speakers plus sub-woofer?

Many thanks in anticipation.