Logitech USB headset sound stutters

Recently rebuilt my computer from the ground up (stayed with Win7 though), and decided to check out Comodo as my new firewall solution (previously I had a package supplied via my employer). While everything runs fine, since rebuilding the box I noticed that when I play video or audio files via my USB headset (H390 - no drivers), the sound would be stuttering every few seconds. I’ve checked playback settings, codecs, players and even my dual-boot install (for games and less trusty software that I can ■■■■ away without worries), and had just about gotten to the point of throwing my hands up in the air when I read on an unrelated forum that AV software can cause issues. So I disabled my antivirus, which made no difference, but lo and behold, when I disabled the Firewall, suddenly the sound comes out perfectly… Is this a known issue, is it limited to USB headsets? (I have an onboard sound interface, but I don’t have speakers or ordinary plugin headphones to compare.)

For reference, my setup is W7 running on an ASUS Z87 Sabertooth motherboard, GTX650 video, 8GB RAM.

Any help appreciated, as I’m otherwise quite happy with the Comodo Firewall product.