All other things being equal, if there's an option for connecting two components using RCA cabling or connecting the same two components using an optical cable, is there any reason to prefer one method over the other from a pure sound quality/fidelity perspective?
I've seen similar questions raised elsewhere, but they usually just end up with someone stating that a digital connection will get you more channels/speakers and is therefore "better"; however that's not really the question. The question is more about which, if any, preserves a more accurate signal (as measured by the difference between the played/recorded sound on device 2 and the original source waveform generated/sent from device 1) between two devices.
If there are caveats that require assumptions to be made, then please assume something along the lines of:
- The source audio is stored digitally (as MP3, FLAC, etc.)
- The distance between devices is < 50 feet
- Both devices are of reasonable and approximately comparable quality
- The source device has RCA and optical outputs, and the receiving device has RCA and optical inputs
Is there a clear and general "best" option for connecting the devices, is it basically the same either way, or does the answer depend entirely upon the specific devices being used?