For me the following (or suitable abreviations)"

iTunes
iPod
Sonos
PC (or Comp)
Bluray (BRAY)
Cable Music (TVMUS)

also recommend
XM
Sirius

Main system: Cable, Apple TV, HD621, G68D, AC11, 218, DSP7200SE (L+R), DSP3200 (L+R Rear)
2nd system: Cable, Apple TV, MC200, HD621, 568.2, M3100 (L+R)