Sherrif,
I think YamahaAndy is right and your reaction on it is kind of 'sarcastic'.
Perhaps it is you who misses some physical knowledge

Higher samplerates are able to record/playback with better time-resolution. Wave-Harmonics exist far above 20kHz and they absolutely make a difference.

You write about 16 bit and 24 bit rates, what is very wrong. The 16bit and 24bit stands for 'resolution' (accuracy) what is very important for the dynamics in a song. The higher the bit-resolution the better dynamics.

About the HDD's : Don't you know the HDD-capacity doubles (or triples) every year ?
In IT, storage isn't an issue anymore.

Roel