What is Audio Researches best preamp period

I like the ARC Ref 2, the model prior to ARC's decision to go the specialty Russian tube route (that have no substitutes).

The Ref 2 uses eight 6922's in the main unit and 5AR4, 6L6GC, and 6922 in the power supply. A world class preamp by any standard.

The ability to run NOS tubes makes this the last ARC Ref that can be fully tuned up to match your equipment, room and personal taste.

I second Albertporter's opinion.... I have a Ref 2 mk1 and it has lots of bloom..........

SP10 Mark II, killer phono stage.

I agree with Narrod from what I have been exposed to but, I still wouldn't think of trading my Aesthetix Calypso or Rhea in for a single piece of ARC ever made. No way, no how. Cheers!

so what is the differ albert from ref 2 and mk1 or mk2 and what mk1 or mk2 did they change tubes,and are you saying if it is the model with russian tubes you cant tube roll,and how do you tell what model to get