Ok I’m confused after reading threads on bit depth?

So for the threads I’ve read here, and checking a file, when you resample , you resample to 26/16 but the last 4 bits are ignored giving you the 12 bit sound.

If I do that and put the sample to highfi mode, it sounds like the original , how can it be upsampling ?

Also what’s the difference between resampling to 26/12 and just turning a sample to classic mode ?

Cheers

Edit: did some more testing when putting on highfi on a sample I’ve resampled , there is a difference.
I was sitting next to one of my speaker not realising the other had gone into standby. With the loop I was using the difference was much more obvious once it was playing in stereo.
Which begs the question …

I think after the resample the track is put in to classic mode automatically? Is that right ? Why if you have just downsampled ?