Unknown can be a result of never having been given a review in the audio mags, or small production, or both.
I am a big fan of the Classe DR3 VHC, but they never had a review, they only made 166 of them (I own 3, one run stereo and two as bridged monos) and they were very expensive at the time ($5K c. 1987.
If you ever get the chance to hear them don't pass it up, and if you see them for sale (a very rare event) consider them. They will drive literally anything (including Apogee Scintillas on 1 ohm setting) and sound almost tube like.)
Downside is that they are very large (too high to fit in regular racks with fixed shelves) and quite heavy (c. 110 lbs each)