do these statements make sense.

"if you decide to upgrade your sound card to a decent card, perhaps an Asus Xonar DX or similar, and then use the analogue outputs you may get an increase in quality"

"Because the assumption (and it's not an unreasonable one) is that the aftermarket soundcard - which will provide the signal, will be better than the soundcard in your Z5500 unit. Provided it can accept analogue.

You need to get past the idea digital is 'better' - it's not. It's just 1s and 0s and data. The conversion from digital to analogue (so your speakers can play it - because all speakers are analogue) is the important thing, as is the quality of speakers. "