Glockenklang 2-Band Electronic Stacked

I Use it with fretless Bacchus Handmade series Jazz Bass with ebony, polyurethane flooded fingerboard.
PRE STORY. So, I had very cool passive bass that sounds great in bass amp. But sometimes, especially at home, i playing in line, or directly in guitar power amp without preamp. Because of the high output impedance of passive pickups, treble was sounds friable and not convincing. And i decided to get some onboard preamp. There was no good preamps for my purpose in Moscow. I searched some solution and found it on Thomann. Good price, the manufacturer and the reviews argues that there is "no difference between active and passive mode" and it's suitable for standard JB pickguard. Two weeks and this device was in my hands.
REVIEWE. Installation is veri simple if you have basic skills with a soldering iron. Good, simple and informative manual was includeded. Minimal size: if you have active bass this device plugs whithout problems. Passive may require additional milling for the battery. Manufacturing quality is wery well: plates is reliable, capacitors - WIMA, potentiometer - MEC. So, as i ensured, difference between active and passive mode is really very small. No boost, no specific voice of preamp - and it's what i need. That's sound of my instrument, and I can get it anywhere with same temper. In addition to low output impedance I got an opportunity to active tone control. So, it's very cool stuff - useful frequencys (40Hz & 18kHz) of bass/treble cut/boost makes good tone in all positions of control knobs, without empty or slicing ears sounds.
TOTAL. Good price, good quality, good sound (if you need natural sound of your instrument with additional features).
P.S. Sorry for my English.

Great product. I have installed it on a 5 string 35" Jazz Bass onto the original vol/vol/tone plate. I needed just a little more space underneath and it worked great. The sound is amazing. It is exactly what you need in a live performance. No hiss, no over the top bass or high frequencies. Very easy to use. You never get lost because it is straight and simple. I totally recommend it as an upgrade. I shall have it installed again.

First of all I'll write my problem: It doesn't fit into my guitar. It's a Ken Smith Design proto J 5 fretless, so if you own a Jazz Bass style guitar measure and think twice (the installation depth isn't the problem, the stacked treble/bass knob's width - in my case)
And these were the cons...

The installation manual is just perfect, simply. If you know as much as me (well, not too much) you'll have 0 problems to install it. I tried it, when the soldering was done, and I was amazed how clear and natural it's sound. I have Bartolini 57J1 in it (needed to mill the bridge P/U hole as well), and it's an ideal choice for it.

Final words: If you want to hear your pickups' or instrument's natural sound it's your preamp. It doesn't color your sound, doesn't add anything to it. I think this is the real Deutsch Qualität...

PS: sorry about my english, it's not my native language.