It's not. You need great ears and even greater hardware to distinguish it from uncompressed in AB testing (on recent enough LAME encoder).
But if you must, go 192k/256k, which is pretty much guaranteed to be indistinguishable for almost all wetware/hardware combination in the world and would still get you about 12h in a gigabyte.
But if you must, go 192k/256k, which is pretty much guaranteed to be indistinguishable for almost all wetware/hardware combination in the world and would still get you about 12h in a gigabyte.