I have 2 dell THX Altec Lansing ADA995 5.1 surround sound speaker systems on 2 different computers. Both computers make a loud snapping sound when turning on and shutting off the computer. The problem may be due to the sub has an amp which is always powered even after the computer is off. I have seen sound cards with a low pass filter and high pass filter, would either of these help prevent my problem? Is there a resister I could use to prevent this problem? I really like these speakers. Thank You, Ed

 

Rephrasing the question: Do I need a special sound card for externally amplified speakers? I have seen sound cards with a low pass filter and high pass filters for sale, I’m not sure if one of those would prevent my problem? Or is there a resister I could use on the sound card to prevent this problem? Other than that, I really like these speakers. Thank You, Ed

 

I can't properly answer your question, however, I noticed that once I installed Linux on an old computer, the speakers would behave as you've described, though it didn't when it runs Windows.

A low pass filter might help, but it would have to have a cutoff frequency above/around 20KHz...

 

If the external speakers are plugged into the headphone out socket it might be direct driven with a push-pull amp chip. That will give DC level issues when the power is turned on/off.

You could try plugging it into the lineout connector instead, that should be capacitor coupled and may not be as bad.