Experimenting today between 2.2nF and 3.3nF caps. I had also bought some 4.7nF caps, but have never installed them. (Single element, E-Side)
Went back and forth between no caps (regular cable), the cable that I installed the 3.3 cap in a month or so back, and a new cable* that I installed a 2.2 cap in.
Directly into either my EA iAmp or my AI Clarus, without any cap, it's hot. My thumb on the back of the neck is sizzle-y through the speaker. The "attack" of my fingers on the strings is prominent. If I cut high-mids completly to start it's okay, but I felt like it had to played around it a bit.
What worked better was putting a Tech21 Q\Strip in front and going to the effects return to bypass the amps' pre. But, on my "small amp" nights, it was one more thing to bring and a few extra potential failure points.
I originally bought 3.3nF and 4.7nF caps, installed the 3.3 first and played it through the AI almost flat. I could not originally source 2.2nF caps, but I picked some up this week.
After going back and forth between nothing, 2.2 and 3.3nF today, I settled back on 3.3nF. I don't notice much, if any, volume drop, but that sense that my whole bass was mic'ed up too hot and needed either really heavy reductive eq or very careful playing around it is gone.
It sounds really nice. There is still plenty of frequency to work with, if I wanted or needed to eq to the room, but I'm starting in a better place now. I'm not tempted to try 4.7nF, it would just cut more high mids and I don't feel like I need that. It's a reasonable ask of the on-board EQ at this point, if needed at all.
*The other change I made is that I bought this 8" FTM instrument cable to hold the cap, so that I can use any instrument cable. Easy to keep it in my bass case and not risk grabbing the wrong one on my way out the door.
I'm happy with the result. Can't think of a pickup I would rather have and happy not to need additional devices between me and the amp to make it work as I want.