An artifact of the DA conversion are the aliases.
They start at the half of the sample rate.
You don’t want to have them in the output hence there is a filter.
If the DAC is running at 44, you need a very steep filter (brickwall) as you want to preserve the audible range (up to 21 kHz) and has to clear out before half Fs begins (22 kHz).
As it is digital, everything remains the same.
Upsample to e.g. 176.
Of course there will be an alias starting at 88.
Of course we must filter but this time half Fs is far away from the upper threshold of out hearing.
No need to brickwall, a smoother one will do the job as well.
Bit more detail:
http://www.thewelltemperedcomputer.com/KB/Sampling.htm