Actually, The correct comparison would be the Aesthetix Callisto Signature or Eclipse to the ARC Ref 5se, not the Calypso. Here’s a link to a comparison of the Calypso to the Callisto:
https://forum.audiogon.com/discussions/review-aesthetix-callisto-signature-tube-preamp
The ARC uses the 6H30 tube. If you like that tube then ARC might be right for you. You can’t change it for anything else, though. The Callisto has a bunch of tubes that you can roll to tune the sound to your taste, maybe too many tubes for many people.