Ayre AX-7F ... F ?????

I have seen a used Ayre AX-7 on offer on the internet that I'd like to get my fingers on to pair with my CX-7. The seller describes it as version "F". Now, I know versions "E" and "X" but "F" is a designation I've never heard of before.

Ayre aficionados, is there really an AX-7F and where would it have its place in the Ayre hierarchy? Or might someone just be trying to create the impression of an upgrade. (F should be ever better than E, right?)

Thanks for any light you can shed on this.
I suggest you contact Ayre directly.
Try Michael @ Ayre at 303-442-7300 x223.

Or, if you don't wish to pay the cost of a phone call, than post this on the amp/preamp board of Audio Asylum. Charles Hansen frequently checks that particular board.

Good Luck!
Betcha a nickel it's referring to the serial number. When I had my AX-7 upgraded to "E" status, they added an "M" at the end of the serial number. My guess is the unit in question is not an E version.