There were 3 versions of the FET9, which one do you have?
2)Original with e power supply (FET9 on unit and e on the supply)
3)Full FET9e (FET9e on unit and e on the power supply)
I update a lot of fine audio gear. I don't see the controversy. The fact is, most electrolytic capacitors last 15-20 yrs, less if they're in a hot environment or the equipment had been sitting for many years without being used. Rubber gaskets on the caps start to crack and/ or bulge (venting). Replacing them can also be considered a sonic upgrade if the type of caps used are chosen wisely. Fet transistors do not need to be replaced unless they get noisy.
The e power supply was the most significant upgrade. Later the main unit was tweaked, with the addition of balanced input/output, and a slight cosmetic change.
Absolutely contact Jon Soderberg, he was at Threshold for many years during that time. Im sure he could make your FET9 perform as well as any out there.
I will contact Jon Soderberg next week but am still wondering if, following refurbishing, my unit will be an improvement sonically on my ARC SP14. If anyone out there has had a chance to compare a properly functioning "well tuned" FET9 or FET9e to an ARC SP14 I would greatly appreciate your impressions.
FWIW, as far as I can tell the differences between the FET 10 and the FET 10e is that the e series has a beefier external power supply with completely removable (and possibly upgradable?) umbilical cord, a set of XLR inputs and outputs (though neither set is truly differentially balanced), slightly different control options and layout, with different knobs and other cosmetics. I would think that the 9 series would have similar differences, and that a standard FET with e series power supply, would be at the very least comparable to a "full blown" e series.
I believe the SP-14 is somewhat similar to the SP-9. Both of these units had crosstalk issues. As frequency went up, crosstalk went up. This caused a problem with the image to some extent. It manifested itself as a whitish curtain between instruments in space and a lack of silence between them. I doubt the FET9 had the same issues as the SP-14 but remember, both units use older FET technology.
A big thanks to all the folks who have helped me out on this one. I talked at length to Jon Soderberg yesterday evening and he said that I would get a significant improvement with a power supply which he makes which is an FET9e equivalent and with an upgrade recapping of the main unit. So, off it will go to him. I'll report on the results when it gets back to me in a few weeks, since there may be interest in the effects for others who have similar situations.