When I bought my Martin D 35 Custom, it came with K&K pickups installed by Brian Kimsey, who has put hundreds of them in guitars. I thought good, I won't have to pop for a sixth set of Dazzos. Here is what I found. Heaping amounts of low end mud and a harsh high mid peak. Thinking something was amiss, I took my guitar down to Gryphon and asked their staff if I had a problem. They put them into a Fishman mini, and without even playing the guitar, they rolled ALL the bass off the amp's bass control. Then they fiddled with the midrange and got a passably decent tone, and stating that you could get a better tone out of a preamp like a Grace Alex. The pickup was not defective.
You must understand that I came from the perspective of pretty much ignoring the EQ section of any downstream devise, using a RedEye before moving on to SunnAudio, so I was not about to go back. I will be the first to admit the challenge of getting the right set of Dazzos, and I can have Teddy himself put them in. I got the very first set of 50s put in my Martin. I have everything in between including a set of 100s in my parlor.
Not only do I think they sound better, but they never fail to sound good with the EQ set flat on any amp or PA or recording interface.
Any piezo needs a 1meg input to sound good. I suppose good is subjective, but I've heard enough K&Ks into an 800 ohm board to have formed my opinion. I do not consider myself to be searching for the holy grail black hole, but just a pleasing easy to use pickup system. I have also come to the realization of how many people really don't know or care. I fault guitar techs who don't educate their customers. They don't want to tell people they really need to spend around $300 to get plugged in.
I have heard plenty of K&Ks well used with a proper pre with powerful EQ sections, it's just not what I want. One should also note that SBT pickups are not for a loud band, witch is why Anthems with their USTs are popular. And lets not forget the Taylor systems, which to me never sound really great, but can handle any situation. I can't use Dazzos in a band with a drummer, it'd just not the right tool.
Now I have Dazzo 70s in my Guild D 35, witch is right down the middle of the Dazzo range. It is a testament to the guitar's even response, and I suspect K&Ks would work better in that guitar than my Martin.