Avantone CK6 Mods
The Avantone CK-6 is a solid little condenser mic, with a nice finish and accessories. The circuit is a standard Chinese implementation of the Schoeps design. (The company's claims that certain capacitors are upgraded appears to not be true, at least in the sample mic we inspected; we see generic box film polyester caps -- the same caps we've been upgrading and replacing on inexpensive mics for years.)
The core problem with this mic is its capsule, or rather, the mismatch between capsule and circuit.
If you find your CK-6 to be too bright or sibilant for the sources you usually record, we recommend changing the stock capsule for our RK-47.
An alternative option is our RK-12 edge-terminated design, which will give your mic a C414 vibe. The RK-12 is subjectively brighter than the RK-47, but not as peaky/harsh as the stock capsule.