Preamp

What did you have in mind?

We were the first company to produce balanced line preamps, and they are all-tube.

BAT was one of our early customers before they started operations. They make balanced line tube preamps as well.

Aesthetix has long made balanced tube preamps.

IMO the better balanced preamps are also fully differential; if you google 'fully differential tube preamp' and 'balanced line tube preamp' you will get a long list of contenders.

dskinner5

The Ref 5 se has a high output impedance as measured by Stereophile especially in the bass. Steer clear of this pre with the X350.5’s input impedance of just 20k.
" Stereophile: However, at 20Hz the impedance rose to 1447 ohms balanced and 637 ohms unbalanced"

Being transistor the GSPRE should be fine, and I can’t find anything on the Mac’s output impedance at 20hz so being tube it has a ? on it.

Cheers George

I have heard that these 2 are a great match?

Is the impedence a problem mating the REF 5SE with the Pass X350.5, I`m not understanding the whole thing? Can someone explain this to me? 

The 4 preamplifiers that you mention may well be satisfactory. I urge you to explore the Sutherland Engineering model N1 preamplifier. I have been living with mine since January. I wouldn't let it out of my system for anything. It simply gets out of the way. Spectacular!