While $3500 to $5000 is a big jump, have you been to the grocery store lately??
I heard both the Ref 6 and the Ref 6SE a few years ago and there was a very noticeable difference.
YOLO
Audio Research REF 6 to REF 6SE upgrade.
UPDATE””””””””” I just got off the phone with Audio Research about the REF 6 to 6SE upgrade and I was told that the price of the upgrade went up from last year from $3500 to $5000. I was pretty shocked. Also he said that it will not have to be done by the service dept as they have a guy who strictly does Ref 6 upgrades. as all parts are in stock and it will only take 14 days turn around time.