I found a cheap, reasonable solution, for me any way. I bought a cheap set of Sony ear buds. These are different from the typical shaped, hard plastic ear buds like the ones that come with iPhones. These have soft round rubber tips like those on higher end stethoscopes and it came with a variety of sizes. So these fit snuggly in the ear canal and which also works to keep outside sound out. The other thing that makes these work is that there is no 'stem' that comes down from the ear bud itself so the ear muffs do not touch the ear bud itself which helps with comfort.
So, they are more comfortable, help keep sound out even without ear muffs over the top. With the ear muffs on, this allows me to keep tractor noise out and to have descent sound quality without cranking up the music volume. For my uses, this is all I need.