Dan D 'Agostino, Mark Levinson, Jim Thiel,

.
Infinity has gone to the dogs. Carver Corp and Sunfire did fine for a while after Bob Carver left, but both are now defunct.
.

Terrible! You couldn't pay me to buy a Krell or Mark Levinson. Thiels I don't know much about. Krell hasn't designed anything truly new since Dan left to start his own company which is producing the best stuff Dan has ever designed sonically and visually. Some of the best from Levinson started Viola and Viola designs are superb. So to me, the companies have languished after the chief designers left.

.
Levinson started Cello.
.

If only Dan would make some equipment affordable real world pricing, I believe Dan D Agostino is making some of the very best solid state out there, but $85,000.00 for a state of the art intergrated amp, Really?, That intergrated by all means should cost $15,000.00 at best!, and that says volumes at that price.

I think Nelson Pass has, more than most other manufacturers, delivered on the promise of SOTA sound at prices while, still not inexpensive, make a lot more sense than some "other" products out there. As for Levinson i couldn't disagree more- they have been (and still are) making some incredible sounding components for many years. Krell makes good stuff too, but due to CAST technology, you need to get everything made by them in your audio chain including CAST wire, which is simply impractical from a monetary standpoint.
One of my favorite long-time examples of an enduring legacy are ADS speakers, whose designer now produces Aerial Acoustic, which are superb (if a lot more money, but not compared to the present-day competition). I once had a pair of ADS L-1590-2 speakers in Rosewood veneer that sounded amazing and were beautiful to look at as well.