I have actually read over the Humble write up a couple times. It's quite helpful. Actually the last time I looked at it I noticed this:
Clarity Cap SA MKP 630VDC 5% tolerance
Sound: The Clarity Cap range has an overall similarity in tonal balance, going up the range you gain a bit in clarity and spatiality. I find the SA to be neutral with a slightly warmish presentation but also a bit closed-in. Compared to the Clarity Cap PX definition and separation are better, the stereo-image is also little larger. I did find the top end to be slightly rolled-off, not that they lacked detailed but on some recordings I wanted a fraction more transparency - but all in all still very nice. On the downside the "S" and "T" in vocals can be a bit plasticy, this is probably due to the lack in transparency in the top octave, making the octaves below sound a little masked. Making a capacitor using about 90% Clarity Cap SA and about 10% Mundorf Supreme works very well, this tends to open up the top end just nicely without altering anything else.
While he is talking about the SA line this does come fairly close to validating what I noticed with the lower PX line. I am also wondering if using more than one in series (eg. 3rd order network) compounds this flaw as I did not notice the issue, almost at all, when testing these capacitors in series with other brands. I actually liked using the PX in the 3uf position with a standard MCAP, which I also tested. The MCAP is a much brighter cap. An issue that I believe also gets compounded when used in both the 3uf and 8uf position. The two together seem to marry well though I'm not sure how much better this set up is compared to the Daytona/Bennic 1% caps I had in before I this wild testing hair appeared. In fairness though none of my test setups have/had near enough burn-in to fully judge them...
I would still like to hear some of the other budget cap lines like the Janzten Standard-Z and Audyn Q4...