My system is regularly being changed, and I want to understand what types of digital conversion options I have, e.g. HDMI to Optical or Coaxial. Questions: what restrictions are there in file format, bit depth, surround capability, etc. For HDMI sources, I have a laptop computer, a Sony X800 player, and my cable box. My two amps do not have any HDMI inputs, but they do have the others I mentioned. I bought an HDMI switch which claims to do the conversions, but it's flaky.