My default rate is 48kHz and most of my projects are at that rate. Some sample packs that i have contain audio files that are at 44.1kHz so when i bring them into a project I tell cubase to convert them to 48kHz. Is there any reason i shouldn’t be doing this?
I’m not really hearing a difference tbh but I was wondering if most of you are using 48kHz for your projects, also if there are times that you switch between one or the other could you explain why?
Nothing wrong with converting to 48 kHz. It’s been said there are better sample rate converters out there than Cubase’ onboard algorithm (i.e. R8brain Free Sample Rate Converter Tool Software - r8brain - Voxengo - which is free) but I’m absolutely ok with what Cubase does.
My default rate is 44.1, I just switch to 48 for video stuff. Propably just an old habbit. Can’t hear much difference if at all, so best performance <> storage-ratio for me (24 bit of course, no reason to be thrifty with bit depth).
I’m guessing it’s not so noticable when you’re using a few converted 44.1 samples inside of a mix that is mostly 48kHz naturally.
is it in any way more damaging to convert up than down or vice versa?
It’s a good idea definately to convert just the few files to the actual sample rate. Also more convinient 
I’d say - absolutely non-scientifical - there’s no relevant damage done up or down as long as you don’t repeat the process permanently. Wondered about such things myself long time ago and did some tests. If I remember correctly, the up- then down-converted files won’t null with the original. So something’s happening definately. The question is if it’s relevant to you with the thing you are doing. Guess, a lot of sample intensive music is done from mp3 loops anyway - from that perspective 44 > 48 is a first world problem only 
Technically (and sonically with high fidelity samples and good monitoring) upsampling from 44.1K to 48K sounds worse than downsampling from 48K to 44.1K.
Why? When you downsample, you are throwing some data away, since a 48K sample has more data than a 44.1K sample. But upsampling from 44.1K to 48K, you are having to interpolate and actually create data to make up the difference.
It really comes down to if you like the way it sounds, or not, since grainier or grittier may be just the thing. Or maybe not.
Using a high quality SR like R8Brain to batch convert, as suggested above, will result in better quality conversion. Only you can decide if it’s worth hassle to you. R8Brain is free. Take a few samples, convert both ways and compare. Great learning process.
This is exactly how I work now for years… I run 32/48 projects… All my samples convert up from 16/44 to 32/48…
I have no math to back up my statements, but I feel it sounds better especially in the top end. I do have some better quality samples that don’t have to be up sampled and that’s nice addition.
When I have all 60 or so tracks running in 48 I can hear better depth and separation adjustements… I dither using the apogee to 24 bit. I release 24 bit 44.1 files. Honestly though, I think my distro does the conversion from there…