PC audio second rate quality?

OK, so I've replaced the CD player with a PS audio DAC and using the Pioneer Blu-ray as a transport and the improvement in sound is a lot better than expected, my attention is now drawn to the sound quality from my PC. It's generally very good but the Pioneer/PS audio combo leaves it behind.

 I've replaced the standard USB with a Wireworld USB cable and things improved considerably, is there any way of improving things further? I have albums ripped to itunes on Apple Lossless and have tried the dodgy WAV and couldnt tell much difference TBH. Would going down the Squeezebox route improve things further? I was avoiding this route due to it's complexity (I'm a computer novice) or should I just accept that PC audio wont compare to a transport/DAC combo.

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