At the second service this morning I decided to solo the bridge pickup on my Brubaker Xtreme 5. The complete opposite of not enough mids and I kept the Quilter flat.
I found that if I want to get silly with the mids:
As a general rule I use the passive input with all of my active basses. The only reason I wouldn't would be if I were overdriving the input, which was an issue I had with my Veyron. All of my Brubakers have Bartolini NTMB preamps and I set the internal boost control at around +10dB. That's hot... and the Quilter handles it perfectly.
1. the 2nd tone control: turn to around 2 or 3 o'clock. This rolls of some (not all) highs. If you have too much highs at the bass, address that too.
2. Pull back the Depth until the mids come forward.
3. Gains: Turn up the gain and/or master. Apologize later

. Keep the bass' volume up, lowering it is the easiest way to lose mids IME.
I gave the band a beating second service... and they loved it. Welcome to punchtown, population me. It can easily be done with the BB800, just not in the usual way.
BTW I didn't do any of these tweaks with the setup I use to get more mids. Didn't boost them at the bass either. More volume with flat treble (which equals less perceived volume than with treble forward) gets it done for me. Favoring the bridge pickup does the trick.
I tried the B/amp, nice... but I don't have anything that needs that much fixing. My $150 Samick Greg Bennett Corsair kills with my BB800 set flat.