I've got the walker's quad muffs and there is no hissing at all with them or none that I've noticed anyway. I saw in the cabela's book that they now have digital muffs and I think they are a little cheaper (price) than the digital ITC Rebel Hog is telling you about. If I had the money I would have went with the ITC (in the canal) instead of the muffs because the muffs get a little hot as I'm sure you already know.