I still think an external DAC and a dedicated headphone amplifier would be a better combination
IMHO - I would look at the webpage I linked to.
There is a UK distributer for the DAC fully assembled:
http://epiphany-acoustics.co.uk/our-...ature-usb-dac/
There is also a matching headphone amplifier fully assembled:
http://epiphany-acoustics.co.uk/our-...one-amplifier/
The combination comes to around £200 and will offer decent sound quality
IMHO,and certainly reviews seem positive from what I have seen. The amp has got good reviews from places such as Hi-Fi Choice and Hi-Fi World.
Moreover,the DAC is USB powered and the headphone amp can be powered of AA,meaning if you are travelling,the whole system is powerful.