Thiel Owners

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. 

@sdecker, 

thanks for the specifics. It's helpful.

 Checking the c-j website:

https://conradjohnson.com/vintage-conrad-johnson-products/

It turns out that the output impedances aren't quite as severe as I thought. I might have been confusing the Audible Illusion pres with them. In any event, unless one is using some weird esoteric cables I doubt there should be many issues with that. On the other hand, the gain and output voltages can be even higher than I thought. 

Let me compliment you on your choice of the Sonic Frontiers pre. I am  a huge fan. I typically fall in the ss camp, but the SF models are exceptional. A dear friend had an SFL 3 that I heard quite often. Despite rumors of troublesome volume controls; count me as mightily impressed. One of my all time favorites.

tomthiel

Yes- I remember reading about the Mod Squad in magazines back then. 
I had forgotten that aspect of Steve. Thank You for the audio history refresh.

Happy Listening!