
Promethus also owns the Piano Forte series sia. Lol just realised dunno was it pure concidence or what, but you also bought the CK100PRO's shortly after i reviewed them here. I can def tell you from my personal listening experience the CK100PRO's and my PF IX's that I also own are at the drastic different ends of the pole in terms of overall sound sig, and even as a self-professed ATH lover I have to say for alot of jazz and classical/symphony genre of music out there the PF IX's even exceeds my ATH AD series at home in terms of naturalness in timbre, and soundstage wise the Piano Fortes definitely has alot of air up-top, w/o any sort of constrained soundstage properties like a typical IEM actually.
According to FAD themselves, the Piano Fortes are engineered/tuned to sound more like true horn speakers as part of their own OPUS series, which FAD was involved with last time as covered in their japanese mag reviews, but you can't find the Opus horn speakers on their website now cause i believe it's an old product. I also believe their excellent resonance/reverb properties in terms of their bass decay/soundstage has alot to do with their respective metal alloy housings these are clad in, I chose to go with PF IX last time cause I demo-ed the VIII/IX and I preferred the latter more.
You should prob get a chance to listen to the Kaede's first b4 considering, forum member shsh91 has them apart from the Flat-4 Sui's and I have met up with him personally to audition it since Jaben has limited sets for this model since this is a limited production release but they are not willing to open it for customers for demo purpose unless u are buying. From my very brief impressions of these tested with some gd quality tracks from Corrinne May/Oliva Ong in FLAC, these have a gd kind of refinement to them akin to EX800st/EX1000 the Sony EX monitors, soundstage is impressive and lower-mids/midrange has good body, definitely doesn't sound thin to me at all.
I will consider the Kaede's to be perhaps a much more refined EX1000's but w/o all that peaks/sibilance issues in the treble that some ppl have complained abt prev, but to clarify upfront both me and Guan22 don't have any issues personally with EX1000's treble brightness at all. (as he had shared once with me b4 in our PM conversations) The Kaede's and the 1st model Sui's does have a slight laid-back presentation in their upper-mids from the 4kHz to 6kHz according to my exp, but from my basic understanding of reading their japanese reviews out there this is purposely tuned by the Ocharaku sound engineer who used to work for Sony, for a non-fatigued long-term listening experience so if you prefer bright stuffs such as those from Grados/Beyers, then the Kaede's are definitely not meant for you.
Cheers bro!