Best bitrate to encode MP3 files
Best is a rather vague description. In terms of sound quality the best is the highest, i.e. 320 kbps. However, this would result in larger files, while space is a problem even in the TB days since music collections tend to become really huge.
I’ve been experimenting a lot in order to make sure I will find a golden measure, to combine the lowest possible size with a quality that would not be inferior (at least so far as human ears can tell) to how a CD sounds.
Comparing mp3 encodings with direct reproduction from my CD player, then with flac, ape and wav encodings, in bitrates of 128, 160, 192 and higher: MP3 files recorded in 128 kbps are not acceptable, although sometimes this encoding is described as “CD Quality”. It is not. This is garbage. MP3 encodings of 160 are better of course, yet still noticeably inferior to CD sound.
Human ear will not be able to tell CD sound from and MP3 file encoded in 192 kbps rate. Differences here appear only very seldom in some special quality albums in certain instrumentations — let’s say in about the 5% of music.
Therefore, the best encoding, the one that combines quality with saving some mbs, is the 192 kbps. Personally, I encode in VBR mode, having the free version of XRecode configured to not go below 192, but to take advantage of the 320 bitrate whenever such an ‘upgrade’ is supposedly needed for certain, more ‘demanding’, passages. This way I sacrifice some disk space but I feel more secure — a security rather psychological, I must admit, since my experiments prove 192 kbps rate to be satisfactory.
I used as a testing system Monitor Audio S6 speakers, Rega Mira 3 amplifier, a Rotel CD player, and, on the PC side, Winamp playing with the Kernel Streaming plugin, connected to Musical Fidelity V-DAC, and mostly classical music of all periods.
You may like to check also this post on best freeware for PC Hi Fi.