I did a lot of pre-amp experimenting on the Century I had, also a lot of pickups as well. In a Roscoe I have always been a fan of Demeter and it will always be right at the top if you want the modern tone. If you call in the morning James Demeter normally answers the phone.
Demeter/Roscoe - A real modern tone, glassy highs, scooped mids and very tight bass (though some say it scoops the mids too much) and works well with both the Roscoe/Barts and the Classic Barts.
East Uni-Pre - A nice modern sounding pre-amp with passive tone control. It has a Vol/Blend stack, Bass/Treble stack, Midrange/Midrange Freq. stack and passive tone which works in active as well. Absolutely kills with Delano pickups and sounds really good with Aguilar DCB D4 pickups
ACG EQ-01 - This is a Filter so no 3 band, it comes with Volume/Blend stack, 2 Low Pass/Filter stacks and a High Pass Filter. It sounds best with the Delano pickups and the Aggie DCB decent but not as good. You can get some solid bass, you can really tame any honky mid-range but you have to use the high pass filter sparingly as it can sizzle quickly. This pre-amp changes the character of the Roscoe tone more than any other pre-amp.
East U-Retro Deluxe - This is an all around nice sounding pre-amp. Sounds really good with Delano pickups followed by Aggie DCB and Barts. The Uni-Pre has kind of taken the place of this pre-amp but I have seen used ones go for around $150 and worth it. Mine had the Active/Passive Switch and Blend Pickup Switch.
Pope Flexcore 4 band - Pope has put together a good pre-amp that sounds really good but I found myself constantly tweaking on it. If you have a wireless pack for your bass you can dial this pre-amp to any room. With wireless you can walk out into the room and dial the mid to cut through nicely and hit that sweet spot to cut through the keys. It sounds much better live than playing in your room. My issue, when you get it to cut and you are using IEMs the tone to me was almost like fingers on a chalkboard to my ears. Using it without IEMs you will cut through and you will be heard. I used this with Roscoe/Barts and Bart Classics.
Bartolini 3 band - This pre-amp will be less mid heavy compared to the Aguilar and is a good all around pre-amp, nothing spectacular but does sound decent. Used with Roscoe/Barts and Bart Classics.
Glockenlang 3 band - Is a want to be Demeter. The bass and mid were similar but the highs just didn't sound natural. I used Roscoe/Barts and Bart Classic pickups.
Aguilar OPB 3 - Didn't care for the mid tone though a lot of people love it. To tame the mid beast I changed the 50k pot to a 100k pot on the mids. I believe that was the ohms of the pot, what ever it was I doubled the value which allow for a better sweep and made the pot not as sensitive to a small adjustment. I used with Roscoe/Barts and Bart Classic pickups.
EMG 3 band - I bought this pre-amp used for $50 and a week later sold it for $50. It works well with EMG pickups in an old LG I had but with any other pickup, meh.
Audere 4 band High Z - I consider the model they made for Roscoe to be the biggest POS I have every experienced. Well, I don't limit that to the Roscoe/Audere as I bought one with the adjustable pots as well and after spending hours of trying to dial in a good tone on a Roscoe, I gave up and sold the pre-amp. Used with Roscoe/Barts and Bart Classic pickups.
I feel I left out a pre-amp along the lines and if it comes to me I will come back and edit the post.
Owners or previous owners of the Century Standard 4. Have you tried any other preamp/pickup configuration than the stock Aguilar? If so, what was it and how'd it fare?
I'm not a huge fan of Aguilar, (I like em but don't love em), and I'd like to try a Darkglass Tone Capsule with Bartolini pickups (P/J).
Any thoughts?