What's the best Tube DAC you have heard?

Hi,

Just like input for my next system upgrade. In attempt to add the tube magic back into my system which currently isn't friendly for tube amps. I'm thinking of adding that magic in the other end of the chain at the source. I do mostly computer served music these days...~40,000+ songs in my server.

I do still spin a record or two here and there, but been relying on my computer/Linn Majik more and more. I'm thinking of switching to a combo of Musical Fidelity V-link async USB -to-S/PDIF and I'll tie that to a good tube DAC.

So would like folks guidance, I've been leaning Audio Note and Audio Research....

Gerald