If you are using an external DAC the transport (cd player, laptop, etc) component doesn't really matter that much. The DAC does the hard part. The transport part has an easier job and depending on who you ask how much difference it makes the answer will range from nothing at all to huge.
I am part of the group that believes the transport doesn't matter much, so if you have an external DAC you can use any device as transport and it will sound pretty much the same. There are few reasons why I prefer a CD player over a computer though. Biggest of those reasons being that computers have fans and other parts that make noise.