Difference: Cary SLI80 Signature vs non-signature?

IF you really want to get the sli-80 call Upscale Audio and get the F1 version, they are the only dealer that can sell it. I have owned 3 sli-80 and this is by far the best. Talk to Kevin or Jared they will help you out.
I have had 3 of them because everytime I sold one and went to something else I ended up wanting the Cary back...they are that good.
Hope that helps.
Mike

I know F1 version is the best of three, but it is out of my budget. Mike, can you give me some detail of the non-signature and signature?

Anyone know?