[HELP] Not considered file size, WAV to AAC the lossless way?

[ssdde]

if i want to convert a WAV file to AAC, no consider the file size, only need the best quality, so the best lossless way is?

my solution is like this, but i don't know whether it's the best quality as possible as the original WAV. (WAV is about 500MB, after convertion below, AAC is 60.4MB)

1) import wav file

2) in Audio tab setting like this,