Metrum is still very much in business. I've had recent discussions with both Cees and Roelof Lochmans who both returned my emails quickly and were of great assistance.
Roelofs email is roelof@metrumacoustics.com
I just recently upgraded my Metrum Onyx with four DAC 3 chips from Metrum and the upgrade was worthwhile. I had discussions on this DAC3 chip upgrade with Cees who basically said the Onyx would be at 95% of the Sonnet level and very similar to the Pavane level with the chip upgrades. They were not cheap so YMMV.
Roelofs email is roelof@metrumacoustics.com
I just recently upgraded my Metrum Onyx with four DAC 3 chips from Metrum and the upgrade was worthwhile. I had discussions on this DAC3 chip upgrade with Cees who basically said the Onyx would be at 95% of the Sonnet level and very similar to the Pavane level with the chip upgrades. They were not cheap so YMMV.