Who are the most underground high-end companies

I've bought wonderful speakers HPS-938 from Hyperion Sound.  This company participated in one show, had no advertising at all and very small dealer base.  They are deep below the radar today, since they went bankrupt.  

Other somewhat obscure companies that make noteworthy products include:

Neat (speakers that are reasonably priced)
Gradient (speakers, like the "Revolution" that are very flexible in terms of room placement)
United Home Audio (refurbished and improved reel to reel tape machines)
Odyssey Audio (high value, reasonably priced electronics and speakers)

Enlightened Audio Design (EAD), Dunlavy, SVS just to mention a few.

If I hear about it (and especially if I own it), it is no longer under the radar. Seems more common in Europe or Japan. However, if I can suggest a three names that have not been mentioned

Burgess
Border Patrol
Ancient Audio

The first two that come to mind are Convergent Audio Technology and Spectral - very little advertising, but generally recognized as making fantastic products.  If you want to go further off the grid, Wavestream Kinetics (product of Scott Frankland, the "F" from MFA) makes fantastic preamps, but again, almost no ads or publicity.