I have the ARC one you mention and, now that I have had the issue of tube replacement and re-biasing dealt with, am very pleased with it. I can't speak for the Mac, but I don't think anyone can go wrong when buying tubed equipment to go with ARC as it maintains its resale value more than well and ARC has always been very good to deal with. They have replacement parts for older units available and, although they are pricey, offer upgrades on a number of products.
