Speaker/Microphone Input Issue

I have an iMac, the newer version where there is only 1 input for microphone and speakers; could having speakers plugged into the port cause issues with the speakers buzzing? The speakers I have are the Hercules XPS DJ Monitor speakers, I'm wondering if this is what is causing the issue; I changed the wires in the back (Red/Black) and it helped a bit but there is still an issue where it is randomly buzzing then goes away (its making me wanna smack the crap out of them when it does it).

Anyways Im wondering if this would solve the issue: http://www.amazon.ca/dp/B00OJ5AV8I/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid =2PDZ0YVK7BCUZ&coliid=I1JWGU3KMXRCKA

If anyone can help me I would greatly appreciate it!