Hi Guys, Thanks for the helpfull suggestions, I set Bitstream DSD in DoP still buffing, tried all the WASAPI settings, still buffing, the files are on my Qnap NAS drive, I had the laptop on mains power, hard wired to ethernet, the drivers are downloaded from the ATC website, they have a setup for the ATC CDA2-CD-DAC Preamp images attached, using these settings the problem files are Flac 192KHz 24 bit and DSD 256, Flac 44KHz and 96KHz 24 bit seem okay, I have contacted ATC but still waiting for a reply
Thanks again for the help
Steve