I like the
D-OAC for quite transparent compression, within the constraints of the vactrol/led timing characteristics ...
Of course, mastering needs a lot of matching across the left and right channels, as well as repeatability.
One can easily build it with some quite close tol switched rotary 'Input' and 'Output' controls
I like the ebay ural 24pos populated attenuaters ... with Dale resistors no less. Still very affordable, considering the effort
I did myself a couple of times, now I just get the ebay HK ones!
Other than that, a trimmer in the 'vactrol-led' sidechain for matching response as best as one can.
The pcbs are easy and the stock circuit showed a high degree of left/right matching with common tubes and components, in my build.
There was a 'vactrol/led' pcb floating around, to clean up that functionality of the pcb (which is a little clunky as is, imho).
The circuit itself is very clean, in terms of THD and the output stage has some nice features - very quiet in terms of hum and noise floor is exceptional - I used a toroidal on board psu traffo.
I used Jensen input traffos and Carnhill output traffos and EH toobs - that's certainly a great combo!
So - D-OAC from Analag/Silent Arts gets my thumbs up - carefully put together can be great for mastering.
Good luck with it!