Mike,
So, have you decided not to get the Sennheiser G4me Zero black, nor any other headphone? The STX has a nice DAC, Amp, and headphone output with Dolby Headphone which makes normal stereo headphones sound like virtual surround, very good. It also has a stereo RCA output and an optical output for either stereo or Dolby 5.1 encoded output. The STX is very nice for movies, gaming, and music, if you use headphones or an AV receiver with 5.1 passive speakers.
When you say 5.1 multimedia Edifier speaker system, do you have these?
It looks like the M1550 only has analog inputs, so you wouldn't use digital at all unless you have the S760D system. An analogue 5.1 active speaker system is off topic from this thread; I can tell you that a 5.1 active speaker set + STX is not a well-thought-out system. If you have more questions about that, you will get better help if you post in a thread about soundcards or speakers.
So, have you decided not to get the Sennheiser G4me Zero black, nor any other headphone? The STX has a nice DAC, Amp, and headphone output with Dolby Headphone which makes normal stereo headphones sound like virtual surround, very good. It also has a stereo RCA output and an optical output for either stereo or Dolby 5.1 encoded output. The STX is very nice for movies, gaming, and music, if you use headphones or an AV receiver with 5.1 passive speakers.
When you say 5.1 multimedia Edifier speaker system, do you have these?
It looks like the M1550 only has analog inputs, so you wouldn't use digital at all unless you have the S760D system. An analogue 5.1 active speaker system is off topic from this thread; I can tell you that a 5.1 active speaker set + STX is not a well-thought-out system. If you have more questions about that, you will get better help if you post in a thread about soundcards or speakers.