There is no more "resolution" when increasing the sample rate of a recording, only increased bandwidth.
The difference between 44.1 and 48k is inaudible in a well-designed convertor. It will shift artifacts only slightly. You will be increasing the max frequency recorded from 22k to 24k, only a small part of an octave at this frequency.
That said, in lesser devices with heavy artifacting, shifting artifacts a little MAY be audible since different frequencies will be aliased and will re-enter at different places, though I haven't found a piece of gear on which it was audible in a really, really long time.
I offer this story as an example which illuminates the value of increasing sample rate:
I once was called in to put together a country studio for one of my clients. He was doing a new record that would be very, very acoustic in what was to be a gorgeous room and was curious about doing it at 88.2.
I told him it definitely made a difference as the tracks stacked up and as you began applying eq and dynamics, but that it would be a major commitment since this was before PT HD and it would require using Nuendo and host-based recording.
Armed with this info, he went to his producer and engineer on the record, a team that had worked together for 20+ years- on the same records, made in the rooms, with the same gear, on the same monitoring, every day for a couple decades.
They had two totally different responses:
One said absolutely, it made a difference, the other said no way, it wasn't worth it, hogwash.
I was a little mystified, because in every way, these guys hear the same and think with one brain.
When I began talking to them, I found the difference:
One had evaluated high-res on super-badass convertors, on two-track material. He had found only subtle improvement.
The other had evaluated high-res on some fairly cheap stuff, transferring multi-track and trying to mix. He'd found a huge difference between working with the 44.1 and 88.2 transfers.
So the ideas are:
Nyquist being what it is, phase shift and aliasing are necessary aspects of digital recording.
Recording at increased sample rates pushes the artifacting of these phenomenons out-of-band, above where we hear.
Cheap convertors benefit greatly by this.
Great convertors benefit less.
As you get more tracks and manipulate them, the benefits become more apparent- as you eq and compress, you work against the artifacts at 1x, but at 2x or higher, the artifacts will be out of band. It's easier to get a smoother, more "analog" mix when working at high sample rates. EQ and compression take hold much more naturally without feeling like they add so much bite.
YMMV, but working at a 48 over 44.1 won't sound better, though it might sound a little different on lesser gear. You will still have in-band aliasing and phase shift, it will just be different since aliasing is not musical (think ring-modulator) and will give different artifacts.
Working at 48k, in general, for music, is a bad idea. It CONSTANTLY leads to confusion and problems since most people by default work at 44.1... witness the number of mixes that still come in on IMP at the wrong speed:)
And while shifting from 44.1 to 48 for your samplerate in record/mix will only make your aliasing different, applying SRC is truly destructive- it is just adding another eq to everything.
-rob darling