Have you tried other headphones/earbuds? Maybe the Clips were different from the Clip+'s? Headphones/earbuds would make the largest difference in perceived quality and tone.
Since audiobooks are usually encoded at a lower bitrate because high fidelity is not needed for understanding spoken word, yours is an unusual complaint. Not illegitimate, just noting that I can’t judge whether the Fuze or Fuze+ would sound good or not to you, even though I have all the players you’ve mentioned. I don’t have “golden ears,” but it sounds like you do.
