Hi GuySmileysMonkey,
Well took my laptop to my dealer, they connected it to an ATC SIA2 - 100 which they confirmed with ATC is the same DAC-Drivers_Electronics, anyway it started playing a DSD 256 file very well then the buffing started, so I tried a Flac 192k 24 Bit file and the same problem, we was not on internet these were files on the hard drive, anyway they phoned ATC and spoke to the technical guy, so he is going to come back to me next week, so no answers yet but at least it happened on another unit, I will update you when I get more info.
Steve