Originally Posted by Mr Pink57
I've heard that say Foobar2k upsamples everything to 24bit regardless?
You can set it to output 24-bit depth, but no upsampling occurs, it simply adds zeroes to the signal. In other words, it does nothing, but then if you play some 24-bit music, it will not get reduced to 16-bit depth.
Upsampling/downsampling/resampling is done through the PPHS resampler or the sox resampler. They will up-/down-sample the music's sample rate to 32kHz, 44.1kHz, 48kHz, 88.1kHz, and 96kHz (and more but those are the main ones most gear will take in one way or another).