Set the volume, treble and bass controls on the instrument at 75-80% of their travel. There is plenty output, you don't need to set everything on 100% and it gives you some wiggle room should you need it (like for balancing the volume between series and parallel). Keep it passive - I really find the active thing (which is just a line boost, nothing more) rather pointless given how hot it is anyway.
According to your signature you use an Ampeg SVT3 Pro. I feel a bit silly and like I'm being cheeky and telling you how to operate your own amp, but I'll ask the questions anyway.
Have you tried using the -15dB pad switch (even if the L-2000 is in passive mode) to give you more travel on the gain control?
Have you set the gain while plucking strings as hard as you are likely to for your playing style so that it's just tickling the peak LED?
Also, resist the urge to fiddle with the bass! There are a lot of switches and stuff to play with but your best bet is to work out in practice/rehearsal what sounds best and then stick with it. I know it's rich coming from someone who modded mine to give me even more options (single coil mod giving me the inner coils) but my favourite sound is when I'm using both inner coils together (in a parallel fashion) - it's kind of like having a third pickup in between where the two actual ones are. It rarely moves from that setting.
Hope that helps, and please don't interpret the above as condescending, I'm only trying to help because these really are fantastic basses and I'd hate for your judgement of them to be coloured by a negative experience which might not be the bass's fault.