just another update....I bought an assembled DIY DAC kit off the bay for about 36quid.
Being fed over ASIO then optical out straight to the DAC so the digital signal is untouched til I gets to the DAC
I threw a LM4562 opamp in there and it really sounded much better, but then I bypassed the entire output stage completely and sent the analogue signal to my headphone amp and now this thing sounds seriously good! I used to have a X-FI with a bunch of mods which sounded pretty decent but this certainly beats it, and best of all it's cheap! Listening to a few different FLAC rips and there are all sorts of intricacies in the music that are much more audible now
This DAC certainly gets my recommendation!!