avoiding amp feedback

[rick131]

I want to hook up two pairs of passive hard wired speakers and connect them from my c media xear sound card to an old external powered amp (3.5 jack to RCA) but I am getting an annoying feedback hum when the amp is turned on. Does anyone know how I can avoid this?

 

[americanaudiophile]

You are getting hum but you are not getting feedback.
You are probably have a ground loop. A ground loop is cause by more than one ground connection between two audio devices. One is in the audio cable connecting them and the other because the amp and PC both have 3 prong AC plugs. You can try a 3 to 2 ground lifter on the amp
http/www.cablewholesale.com/products/power-products/power-cords/product-30w1-32200.php?gclid=CNGyr7CZiMYCFdSQHwodSJsANg
Or try connecting the amp to a different AC outlet.
There are audio transformers that plug in between devices to isolate the grounds in the audio path too.
http/www.amazon.com/BOSS-Audio-B25N-Ground-Isolator/dp/B000LP4RMG/ref=sr_1_2?s=electronics&ie=UTF8&qid=1434044675&sr=1-2&keywords=audio+ground+loop+isolator
If you haven't use the amp in a while old capacitors can cause hum too.