The transport is less critical in my opinion then the dac and digital cable. One of the best tube dacs are the older Audio Logic 34s that you can find for around $1000 depending on the chip set inside. They can be modified by the manufacturer to current standards if you want. The AL 34 dac has 4 tubes with a separate power supply. The better the tubes, the better the sound. This DAC is better then the original Cal Alpha DAC but go with the non 24/96 version of the CAL Alpha dac. If you find an AL DAC, make sure you do a search on Agon for Audio Logic and what digital cables everyone is using, there are plenty of AL fans here on Agon.
Happy Listening.
Happy Listening.