Van Alstine Vs SAS Preamp

I am looking for a preamp for Hypex NC400 mono blocks. I am interested in the Van Alstine Avastar and the SAS 10A preamp. Anyone has experience comparing these two? How they sound differently?

Never heard a SAS, the AVA is very clear if thats any help.
A guy wrote a review of the SAS pre here on the forum, do a quick search.