24 bit audio files

I would like to have a go at playing back downloaded 24 bit audio files.I note that itunes can replay 24 bit 96 khz  alac files. I use an 8 year old hp pavillion lap top,my guess is that its in built sound card  only works at 16 bit 44khz ,is this likely to be so ? I down loaded a 24 bit 96khz test file from Linn which played fine in itunes , but would it have been - down sampled in some way?