Mike, Anniversary is the quality of Signature with the control layout of Series.

The major difference between Anniversary and  Signature electronics is the ability to run stereo output and separate volume controls for each pickup. The underlying preamp electronics are the same I believe. It is these features that draw the inferences to Series electronics.  
 
Keith

hey everybody. thanks for the compliments.  yes, i am an alembic freak.  i have been the proud owner of 10 custom alembics.  The collection is down to 7 (which includes 2 series I's). I'm probably going to put one more up for sale (a custom short scale spoiler) since its not getting enough needed attention.  tuff times and the birth of my second child have forced me to unload a few of these absolutely beautiful instruments.

This bass has finally found a home, hopefully for a long while!  I am so happy with this bass.  Adam, its as if you knew what I wanted and went ahead and had it built for me 5 years ago.  And the fact that when I brought it home, it smelled and felt like a brand new bass, I just cant say enough.  And it was a steal at that price, BTW.  Thanks Brian at Low End.  My question is, everyone keeps talking about there being all this information on here about the differences between Anniversary Electronics and Series 1, but I cant find anything.  Since this bass has been prepped, I cant decide if I want to send it to the Mothership for the upgrade, or if I want to just leave it as is.  Ive always wanted a Series bass, and that would make this bass a dream come true, but since I actually play it live, and with a wireless, Im wondering if Im not better off to leave it alone.  I have read a thread or two about some folks on here that were able to run both pickups out of their Series 1 without going to the power supply, is this correct?   I just want the ability to run stereo from the output jack, so if it means sticking with Anniversary, then so be it, but if I can do this with Series 1, then Im going for it.  Any advice out there?

Congrats Jeff!!!
 
There is some discussion of the difference between Series pickups and the humcancelling pickups in all other Alembic models here.  There is also a difference in the filters and the filter circuitry, but I don't recall there being any detailed discussion of that difference.  But there is a distinct difference in tone between the two systems.  There are members here who own both and love both.
 
If you get the upgrade to Series, the 1/4 jack can be wired stereo or mono, or both with a switch.  So yes, you can run stereo without the power supply.  However, if you don't use the power supply, you will be changing batteries often.

Hey, Adam, can I ask you a favor?  I love all of your basses that I've seen - could we get you to start a thread in Showcase with pictures of all of them?
 
Peter