My Shertler P48-V pickup developed a cracking bad contact, which made it useless in practice. So I needed a replacement while I (try to) get it fixed. The good advices, the price (the same as a new Shertler cable, which turned out useless!...) made me give this KNA pickup a try. I was also very interested by the wireless transmission, as protecting the fragile cable of my Shertler was ruining my freedom while playing, and having the pickup installed forever seemed so much simpler than having to install/desinstall the pickup each time you play.
Once received, the installation on my viola was very simple, and I could play at a jam session the next evening. And indeed, leaving the receiver jack plugged in the amplifier felt like a dream: no need to crawl behind the drummer to (dis)connect each time I wanted to play or stop playing, I felt the same freedom as trumpet players I always envied for that! Between performances, I could just switch off the emitter, and switch it back on when comes a tune I know and want to play with.
Furthermore, the very light pickup felt like a feather, with no or very little alteration of the sound without amplification: so I can indeed leave it on forever.
The amplified sound is great, much better than other piezo pickups I had tried. I can be optimized as it changes a lot when moving slightly the relative position of the pickup and the bridge. I put the middle of the pickup under the highest (A) string, and added 3 layers of visit card strong paper to ensure enough pressure. It can be further equalized by cutting the highest frequencies, but it can also do without it. Of course, the sound is not as good and warm as with the Shertler P48 (which has a built-in filter requiring the phantom 48V tension), but I was surprised how good it is.
Extra bonus: the pickup can further be connected via a good old mini-Jack-Jack cable. This is reassuring as a backup if you run out of batteries, or if there are interferences perturbing the wireless transmission. I used that feature to try and detect a difference between wireless and cable transmission. I had the impression that wireless was slightly increasing the "grainy" sound of piezos, which overstate the scratching sounds of the bow friction on the strings, or staccato attacks when jumping the bow. But I am not 100% sure: the difference is really tiny!
So all in all: I'm so happy after 1 week, that I am not sure how fast I will try and repair my Shertler. (Feature+Quality)/Price ratio is just huge: my best buy in years!