Audio Research Ref 6 SE

Admittedly an ARC fan, I believe their equipment now is the best sounding it has ever been. The new Ref 160 monos and 160 stereo are knockouts. 
Parts always get better, and more expensive. 
Their press release says that they have taken things they have learned in the development of their "lastest products" and put them in the 6 SE update. The "latest products" are the 160 amps, so they must be using parts used in them. 
In the past, if there is an update that can be retrofitted in a product then they call it a mark II or an SE. If the product can't be updated they usually go to the next number. The LS27 never changed, so when the new model came out it was an LS28.
9rw why don't you ask for a better price on an SE update? All they can do is say yes (happy) or no (not). 

If you've assembled a system with offsetting products, like a warm speaker with bright cables, then you might have bad results when you choose a replacement in that system.
Upgrades need to slap you in the face for the better, or don't spend the money! 
Most equipment gets better over time, it's something we live with. I'll bet the SE is better. The 7 will probably be even better in a few years. In the meantime I will go home, enjoy some music, and relax, whatever is in my system.
Good to hear that Stereo Exchange took care of you.