Agear - look, there is nothing sinister about my comments of tubes not being the best choice for digital. Any EE worth his salt will agree with this. I have 30 years of salt in my ears.
This is a lot like the habit that many designers have to use HC logic family for digital circuits that must maintain low-jitter. Makes no sense at all, except to those that don't understand the physics.
There also companies that offer tube analog buffer stages that don't understand why these are interesting. They actually do work well in many cases. It has to do with replacing a low-drive strength DAC output buffer with one with high drive strength, better adapted to drive a cable with capacitance. The ideal thing would just have a better output stage in the DAC.
There is a lot of blind leading the blind designers out there. Sometimes bad habits and choices get copied. I've seen it all. Even junior designers from Sony making fundamental errors in high-end CDPs. Modding a LOT of components for over 10 years opened my eyes.
Steve N.
Empirical Audio