"hard disk" may now be too loose a term.  PCs and other computers have storage devices, typically spinning 'hard disk' storage.  For hifi 'replay' purposes, that's noisy, due to both mechanical spinning and fan, and to interference from neighbouring electrics.  The solid state storage, such as on an iPod, is also a 'hard disk' but one that has advantages for hifi replay.

Need to tease out some terminology for future use.

Would also need to tease out of 'Other' the AV stuff, the PC etc.