Just as a point of interest, my digital audio workstation (ProTools) has facilities to change the sample rate and create a new file. If I set it to the highest quality setting (they call it "tweak-head"!), it takes several HOURS of number crunching to convert about 45 minutes of stereo music from say 48k to 44.1k. And this is on a fast computer. Kind of makes me wonder about the performance of sample rate converters that do it 'on the fly'....