I have the mk2 version. I’m under the impression it could be modded to mk3 status with a board swap, but honestly the performance is so good, I don’t feel the need. If my Mk2 died today, the Mk3 would be at the top of the list for replacement.
Modestly priced, high value gear doesn’t receive as much attention here as other audio forums, and as mentioned earlier, Garry doesn’t really advertise much.
If you’re considering the mk3, these DACs really benefit from NOS tube swaps. In my experience, signal tubes, followed by the rectifier tube make the largest improvement. I landed at a pair of NOS Amperex signal tubes and a new production Psvane 5u4g rectifier. Cap upgrades offered negligible improvement in my system.