I've been a loyal Telarc fan since its inception, dating back to 1977. I purchased many a Telarc digitally-recorded LP, and used them often for demonstrating equipment for companies I worked for.
Their CD's are absolutely first rate, and the reason is the engineering, most of which was done (on the "redbook" CD's at least) by Jack Renner, who is now retired. It is his efforts with the choice of digital recording devices, as well as meticulous choices in both the quality and positioning of microphones. Perhaps most importantly, none of Telarc's purely classical CD's use any form of signal processing. That means NO equalization, limiting, and most significantly, compression.
Telarc is also an enthusiastic supporter of the DSD recording medium, and its companion playback device, the SACD. My own experience with Telarc SACD's has been mixed, however, as Jack is no longer there, and some of the newer recordings seem to be much too distant with far too muted a sound on percussion instruments, resulting in a sound that can legitimately be called "dull."
Not all Telarc SACD's are duds, though, and some are unbelievably good. As I've posted on this site before, their DSD remastered recordings originally done with the Soundstream digital tape recorder are remarkable examples of just how good the SACD medium is.
Lastly, for those interested in good CD sound, who don't own an SACD player: Telarc's SACD's are all "hybrid" discs, and the CD layer is often quite good on its own.