There is no comparison. The newest versions which use the "super tube", are in a different league. Sonically they are much more accurate, much quieter and much faster.
The difference is even bigger in the preamps, when it comes to the REF2 and the REF2 MKII. There was a mid bass bloat which seems to have disappeared as well as a lowered noise floor.
The difference is even bigger in the preamps, when it comes to the REF2 and the REF2 MKII. There was a mid bass bloat which seems to have disappeared as well as a lowered noise floor.