Im using the Xonar Essence STX RCA jack for external amp use while using the headphone/microphone ports for gaming. I've experienced a slight static/hum sound come on while using the headphone jack whenever a sound is playing. This continues on for a second or two after turning all sound related programs off. I have no problem with the RCA connection, doesn't have the same issue. I thought it was cause grounding error so checked all wires, none seem to be touching. Is this an internal error? Should i warranty it?