I moved from the Zune 30 to the 80 and found this upgrade yielded a nice modest sound improvement. There is not a huge difference by any means, but rather subtle improvements that can be heard with careful listening and good headphones. The 80 is a very smooth, open and natural sounding player with pretty minimal sonic signature. The 80 seemed more accurate, with slightly better air and detail, and feels less “warm” than the 30. I have never felt there was anything lacking or missing with the 80. I frankly never missed the tone controls...but I never really used them or believed in them especially if the gear is accurate. I guess I’m a flat “defeat the tone controls” kind of guy on all my gear. It’s a very musical and excellent sounding device (as many have lamented on these boards) and I have personally enjoyed it immensely.
The other considerations of the upgrade including the improved interface (squircle) size, screen quality, hard drive size, and general fee. These are all far superior on the 80. Even if they sounded exactly the same (which they don’t) I would be using the 80 for these reasons alone. Plus I’ve personally maxed out my 30…now my 80 so I need more room with a 120! The Zune Pass is like music crack…lol!

Plus now you get 10 free (non DRM) downloads of your choice with the Zune Pass every month so it’s an absolute no brainer subscription model if you are a music junkie! Since the price of a 120 is now what you would have paid for an 80…I would get the 120 if I was moving up now. In fact, the 80 might now be “officially” discontinued, but I’m not positive. I’m planning on moving up to a 120 for Xmas so we’ll soon see if the 80 and 120 are the same sonically. I’m reading and expecting they are because the difference apparently is limited to hard drive size, screen, and finish (matt to gloss).
Lastly, I use the UE TF-10’s with my Zunes and have not heard the super fi 5 pro’s. If sound improvement is your first goal (not features, hard drive size, screen, etc.) take the money you would be spending on upgrading from a 30 to 80 (or any other player for that matter) and sell the super fi 5 pros and buy some TF-10’s. Now that would probably yield far more significant and dramatic sonic improvement IMHO. The TF-10’s are simply amazing!
Cheers,