If I was buying used CD player I'd really consider The Oppo BD 105 which has decent internal DAC If go you the new route, the Audiolab cdt is excellant, but it's a transport only and was primarily designed to work with the Audiolab 6000n streamer, and 6000a Intergrated amp. But of coarse you can use them all as standalone. Prices seem to be very reasonable if that's a concern. In this review the gentleman used inexpensive external DAC and also very exspensive DAC's with CDT and was very excited about the results
Watch "Audiolab 6000CDT Review!" on YouTube
https://youtu.be/JAfk5a5M5ds
Watch "Audiolab 6000CDT Review!" on YouTube
https://youtu.be/JAfk5a5M5ds