upgrading Apogee Duetta speakers

I recently aquired a pair of original Duettas that sound wonderful, but like all audiophiles, I am looking to upgrade them to the Duetta Signature level, or at least close. Does anyone know what crossover the Signature used and where can I purchase those items?
check here:http://www.apogeespeakers.com/
I did this journey with Duetta sigs and Divas. They sounded epic when completed. You have a lot to play with.

I would get the ribbons replaced with Graz new ones which are far superior to the originals. Tighter more dynamic, refined and take more power.

The crossover components can be easily replaced with better. Unfortunately it is a large crossover so this may dictate how crazy you go with nice caps and inductors.

The mundorf silver/gold in oil or silver in oils are very nice caps. If that kills you financially try a mix of large cheaper caps made up with or bypassing with the best you can do. Unfortunately duelund caps will be like buying a car. But their sound is almost worth it!

I used alphacore foil inductors. These were very nice. All these mods make the crossover point much more seamless and give much better detail and remove grain. Sound staging improves by miles and bass is cleaner.

Good luck. Feel free to contact me.
About 2 years ago I got a pair of Calipers and restored them. I replaced the inductors with ERSE Air Cores and the caps with Auricaps and the resistors with Mills. Those changes significantly improved the speaker. I would keep them forever, but ...

I now have a set of Duettas (the Calipars are for sale here if you know anyone who wants them). I learned from my first effort and took the crossovers out of the speaker and put them in a separate box. There are lots more components in the Duetta crossover. I found a combination of different caps gave me a better overall sound, using some Auricaps, some original Spragues, some Sinocaps, some Russian PIO's and some Russian teflon bypasses. I also replaced the resistors with Mills.

I decided to put the existing inductors rather than replace them. I used Red insulating laquor available from Allied Electronics. I also braced the cabinet better by installing an aluminum "L" bracket across the back, thereby coupling the interior with the exterior shell much better.

The improvements were phenominal, resulting in a much more transparent and tighter sound while keeping the musicality and imaging that Apogees are known for.