ARC REF 6 upgraded by ARC.

@yesiam_a_pirate   I bought my Ref 6 brand new. It only has 620 hrs on it. Sending it back for the upgrade I will be using my dealer for delivery. 

I agree with @yesiam_a_pirate ,  talk to your dealer about a new 6se.  Avoid the wait and get a new unit with warranty.

Been a Ref6 owner for about  a year, I'd have to hear an SE to prove it could get any better.  Paired with ref75SE amp and Quattro ct's.  I don't think I'd like the 6se if it was "mellower".

Another option would be to wait and have your pre updated to Ref7 whenever that happens.

Someone mentioned doing this yourself.

Back in the "very old" days, ARC sent out kits to us dealers for upgrading the SP-3 to an SP-3A1.  I did about a dozen for my customers back then.  I forget exactly--it was 48 years ago--but as I remember it was about 10 parts.  HOWEVER, upgrading to the D-76A amp was a COMPLETE change inside the case, so it had to be done at the factory.

I would guess your Ref6 upgrade needs the factory people to go through it and make sure everything is right.  It is expensive, but if you love the new sound, go for it.  As the saying goes, “The bitterness of poor quality remains long after the sweetness of low price is forgotten.” ― Benjamin Franklin

Cheers!

It's a tube preamp, not that complicated to work on, you probably would get more for your money with a smaller tech like bigkidz.