I don’t think that Mac is the right amp for the Sabrina X , you’ll have to use the 2ohm tap if it has one, then the wattage might not be enough because the lower the impedance tap the less wattage you get on transformer coupled tube amps, think the same applies with the Mac
I had the pleasure of A/Bing the Sabrina X vs the Salon 2
https://forum.audiogon.com/discussions/sabrina-x-amp-suggestions/post?postid=2125370#2125370
The Ravels are a far better loading for the Mac
https://www.stereophile.com/images/archivesart/708Revfig01.jpg
Cheers George