So if I replaced my stereo receiver with an HT receiver (one that does have digital inputs), and used a fiber optic cable,
that would give me better sound? (I have seen some pretty nice looking HT receivers around $300, which I could manage easily enough.

)
Oh, I forgot to add that there is nothing wrong with how it sounds now. I just like the idea of anything that would make it even better. Spending up to $500 is acceptable if it makes a real difference.