Supratek or Don Sachs - which way to go?

My Cortese doesn't have the two shiny domes. It has compact, comparatively low profile heat sinks. I don't know why some preamps have the domes and some don't. I am guessing that it might have been an aesthetic choice Mick made some time in the past and the original purpose was to improve the looks of the heat sinks. But I'm only guessing. 

Another music lover here who has Don Sachs/Supratek preamps on the mind.
it’d be great to get further insight re: sonic differences and/or if one could/couldn’t pass a blindfold test listening and comparing these units. :)

Having not heard the Sachs, I can't speak to aspects of its SQ, but what impressed me about Mick's vs. Sachs was true balanced ins and outs, a consciously designed modestly warm sound and the lifetime coverage. $500 or so less for the Chardonnay didn't hurt either, but wasn't decisive.

I actually own the latest versions of both the Sachs and the Chardonnay.  For the most part their sound is very similar with the Sachs leaning a bit more to the neutral side and I have rolled six different sets of tubes through it with only slight variances in tone.  In terms of flexibility Highstream is right about that with the Supratek's Balanced and SE inputs and outputs in addition to it's variable 0-25 db gain control and L/R balance control. A positive or negative based on your outlook is the power supply being in a separate chassis.  The Sachs gets the upper hand in remote functions as the Supratek's only do Mute and Volume.  One thing you really need to take into consideration with the Sachs that you don't with Supratek's is amp and speaker matching. As the newest Sachs has a fixed gain of 18db you can't just pair it up with any speaker and amp combo and not get tube noise.  For example in my Main system the speakers are Verity Otello which the manufacturer specs as 93 db.  That is likely higher than reality and closer to 90 db. With the Sachs in the system I started with the Van Alstine Vision SET 400 amp that I bought the Sachs to pair with. It has an input sensitivity according to the designer of 2.4 volts and the combo is dead silent until you put your ear basically touching the tweeter. When I substituted the Kinki Studio EX-M7 with an input sensitivity of 1.45 volts you could hear tape noise within about 2 feet though not noticeable at the seating position.  So no what you are going to pair it with before you buy.  Neither amp would have had any issue with the Supratek and haven't as you can easily adjust the gain on the amp to eliminate the hiss.  So it's going to come down to which features are more important to you in the end for a very similar sound. 

The 10K input sensitivity of my ATC SCM19A actives was also an issue with the Sachs. Don would have needed to use (very good) Mundorf 3 uF silver oil cap instead of his favorite Polish .47 uF oil one for fit in the case, with $125 for the difference. Not an issue with the Supratek.

As you say, one difference is that the Supratek has a separate power supply, which means an umbilical. The one provided is not bad, but my experience is that the SQ effect of umbilicals and even 5v lines can typically be improved significantly (as a textbook engineer, Mick doesn’t believe that could be true). Ironically, I lucked into a cable maker who also doesn’t believe it, but nonetheless offered to make me one in a private deal with the Belden high quality copper with silver plating that he uses for internal wiring of the headphone amps he builds. The result was like taking the Chardonnay a good half step up the sound quality ladder. Revelation Audio also makes them commercially for the Supratek.

My only worry with Supratek is the cost of shipping were a tube socket to go bad.