If I have 44.1kHz sample rate file and convert it to 48kHz assuming non-lossy format (not sure if that's even relevant), what happens? Is it OK to do that? Will hear any difference (I'm not hoping to hear something better obviously) but will there be some kind of quality loss? I just want to make all my files match before I lay them out on the tracks, that's all. I'm not asking how to do it. I just want to know if it's bad to do that or reasons I shouldn't do that.
Thank you
Kathy

Up-sampling should not degrade quality assuming it is in the PCM format, It will not increase the quality though.
OTOH, down-sampling can reduce quality, though down-sampling from 48k to 44.1kHz file is usually not audible either. If down-sampling is necessary, an anti-alias filter is usually recommended.

Up-sampling should not degrade quality assuming it is in the PCM format, It will not increase the quality though.
OTOH, down-sampling can reduce quality, though down-sampling from 48k to 44.1kHz file is usually not audible either. If down-sampling is necessary, an anti-alias filter is usually recommended.

Thank you.

The question is if you can hear the software creating the missing samples - then the algorithm they are using is not too good. In practice, you cannot hear it, but the new waveform is not the same as it was. When the smooth curve is sampled into individual slices, and then extra's are added to replace the 4 thousand missing ones each second, then you have a re-creation - in some music adding an extra in is exactly the same as normal CD/DAT error correction - you can duplicate some frames and few people will notice. Upsampling always degrades, but hopefully not enough to notice.