Fitter and all, the way the upgrade project is shaping up is to target the most mature iterations of separate-driver classic systems first (with exceptions.) There are many thousands of pairs out there approaching eventual electrolytic capacitor problems. The targets are PowerPoint 1.2 (because I use them in my recording /documentation work and think they have serious professional potential) CS1.6 (no expressed interest), CS2 2 (because I use my pair in my work and it is very special) and CS3.6 for the same reasons. These models use Thiel-developed drivers with proprietary and patented technologies, mature enclosure designs and considerable performance upgrade headroom. The CS5(i) is not on the list. Its fundamental upgrade option is to replace the huge bucket-brigade delay lines with a re-engineered baffle to place the drivers in correct offsets for time-coincidence and elimination of dozens of capacitors and resistors in the signal path. I have ideas and skills, but insufficient life-force to take on that project. Similarly the CS3.5. The CS x.7s will come later. They do have upgrade potential, but are stable in their present lives for now. CS2.4 is in the first tier because of broad interest, significant potential and beetlemania's willingness to collaborate.
All models will have an inboard and outboard option. Inboard space constraints limit some capacitor and coil choices, but all electrolytics will be replaced by high-functioning propylene caps, and feed coils replaced with 4-9s foil coils. Outboard applies same strategies with some larger, higher-voltage feed caps and larger gauge coils and optimized layouts. The cap choices settled on ClarityCap and Multicap RTX bypasses, after exhaustive research and correlation with Thiel history and values. All parts are ordered for first-round samples for PP inboard, PP outboard, CS2 2 inboard, and CS2.4 outboard. We'll be making music this summer.
I will be using an unconventional evaluation approach, rather than MLSSA and related lab development and measurement tools, which I don't have, but would love to find a collaborator for. I use Metric Halo SpectraFoo, a pro-audio tool for tuning rooms, performances and recording, mixing and mastering music, along with some precision meters and scopes. Our benchmark method will be the system I use for my professional instrument and music making. We'll record live in my studio direct to hard disc at 24x192kHz for playback in the same recording space through the same signal chain, through speakers under test. We have live thru playback (music or technical content) with very few unknowns and considerable control and documentation of bass, peak and mix levels. The results going in and coming out are all sampled and analyzed via technical measurements and simultaneous listening. Someone could build a speaker company on this methodology . . .
You might notice that this scenario looks like more than an after-work undertaking. It is and I don't know how that will all settle. But I am enjoying this challenge and have high hopes for outcomes. Stay tuned.