Just to clarify, the PicoScope 2204A is an 8-bit resolution device. The 12-bit resolution can be obtained via the PicoScope 6 Resolution Enhancement
It is likely to be a combination of the PicoScope 2204A signal generator and the inputs.
Comparing the specfications for harmonic distortion:PicoScope 2204A:
< -50 dB at 100 kHz, full–scale inputPicoScope 4262:
-95 dB typical @ 10 kHz, -1 dBfs input
The PicoScope 4262 has a lower distortion value.
I also tried connecting the signal generator of the PicoScope 2204A to the input of the PicoScope 4262 and vice-versa with the following results:
The PicoScope 4262 is better suited for audio related measurements compared to the PicoScope 2204A.
The data files are attached below (they were saved using PicoScope 6.11.4 Beta).
Hope this helps.