I get the same issue on a integrated Recon3D on my Gigabyte G1 Sniper M3. With only my old pair of Koss Porta Pros connected to the dark green headphone jack (that is, from what I read, the output of an internal amp). After posting a thread here I realized that I have no clipping (or in my case...

Hello. First time poster here, having an issue. I use Koss Porta Pro Headphones on an Gigabyte G1 Sniper M3 with Soundblaster Recon3D integrated sound.   I get popping sounds at what seem to be low frequencies. It seems a bit random though and doesn't happen to every sound I hear regardless...