Thiel Owners

jafant, just a (looong) clarification.  Steve made a name among the tweakers post McCormack, but the company in its prime throughout the '90s and early-00s was substantial, offering moderately-priced well-engineered preamps, DACs, phono stages, etc. as well as power amps.  They were brilliantly designed, but brought to an affordable price point with modest chassis build and components.  Which is what makes the SMC upgrades so significant -- the basic design can really shine with top components and clever tweakage.

C-J took over manufacturing of the power amps in the late-90s with some consulting from Steve, but he had already started SMC Audio as his next gig.  The later amps built by C-J never had the same success as the earlier California-built amps.  My top-of-my-head chronology may be a little off, but that's the gist.

No overlap in the sonics between the two companies so far as I can tell.  McCormack amps are purely solid-state with a bit of the good characteristics of tubes baked-in to the design.  C-J has kept the classic tube sound more than other modern tube gear designs, but others here could evaluate that far better than me.  A C-J preamp + McCormack power amp would be a good pairing I'm sure; I use an upgraded Sonic Frontiers tubed preamp.

Even earlier history - Steve ran the Mod Squad in the late 80s, early 90s where he kept abreast of evolving digital technologies, offering substantial performance upgrades to CD players (primarily). The Mod Squad's niche dissipated as digital filters and topologies improved. Then came McCormack Audio, etc.

Mod Squad seemed to really start to make their mark with "Tip Toes".

Some conrad-johnson pre's can work quite well with some McCormack amps. But due to the high output impedance of some  of the c-j pre's coupled with the low input impedance of some of the McCormack amps it can be a bit trickier. Furthermore, the high output of some c-j pres with the high input sensitivity of some McCormack amps can reduce the effective range of the volume control. Of course c-j doesn't offered balanced outputs for some of the McCormack's balanced inputs.

All McCormack power amps have a 100k input impedance which is fine for any preamp.  EXCEPT for the DNA500, and its monoblock equivalents DNA750 of only 10k, and I believe these to be the only McCormack amps that offer balanced inputs via a phase-splitting transformer (hence the low Zin). 

Most if not all of his amps do have a high input sensitivity for Steve's preferred (?) passive preamp mating, that forces conventional volume pots to work at the very low end of their range with your typical active preamp with 10+ dB gain.