When you say 'retire' your McIntosh preamp - what do you mean?
Would you 'trade it in'?
I agree with @dean_palmer - McIntosh has an agreement with their dealers (as does many manufacturers). Having a relationship with a local dealer and including 'trading in' your current McIntosh preamp may enable the dealer to present you a deal you find acceptable.
Several years ago local dealer offered me an opportunity to buy used speakers - a model they know I liked and wasn't willing to buy new. They had a long term customer who bought them and after a year wanted to buy a new set of his previous brand of speakers. I think they sold me the speakers for what they gave the person as a trade in value so it would allow them to sell the new speakers and provide a deal for me.