I did mention in an earlier thread that I had ordered a
NOLL preamp to put in my bass with EMG active pickups, to replace the BQC-EMG system that was installed with the pickups.
Let me first say that you can choose the wiring options from a list and I chose one that required 4 holes in the bass because that's what I already had. I chose VOL, BLEND, BASS/TREBLE, and LOWMID/HIGHMID.
Frequencies are according to this diagram
My bass is a custom made Eugen, and I took it to the luthier to have the preamp installed (9V, btw). He did, and sat down and played the bass. His comment "Wow, this is actually a usable treble!", and continued to work the mid knobs.
For myself I can say that this preamp is very musical indeed. I had a gig in a very boomy room last friday, and we had to cut most of the bass frequencies to be heard at all through the reverberation. Then I dialled in some 400HZ from the lowmid knob, and it helped a lot for me to be heard without boom.
I like this preamp, it's much, much, better than what I had. It's just musical, no matter how I dial the knobs. previously I was thinking about changing the pickups, but now I am not so sure
I am also relieved that I am easily able to hear the difference in quality electronics.
Lastly, I might add that Klaus Noll answered emails personally, and quickly, so we could discuss knob colour, 9v/18v and so on. Great service and fast delivery. Oh yeah, I ordered from him directly, and paid 140€ -> 186$ .
Noll 4-band preamp, very nice! 
You'd only hear the characteristics of my particular bass though, probably not too helpful 
