Thanks for that update. I'm not getting another sansa product just because I've had several and always ended up letting them die. I'm glad the zip problem is going away. The clip+ is fine with rockbox as long as you don't use external memory. My earphones are generally 43-55Ω and that noise is terrible. With 16Ω and 112dB earphones, it is simply impossible.
Is this a Clip Zip problem or a Rockbox problem? I never had any sound problems with the Clip+ or original Fuze using Sandisk firmware. My headphones and earphones are mostly from 16 ohms to 63 ohms. I also use some higher impedance headphone with a Fiio E6. No sound problems ever.