I think the fact that Kala has switched to Silver Rumbler strings for the new EQ-equipped Rumbler shows that they acknowledge tuning stability issues with the old black strings. Yes, they do roll a buit under the fingers, but I don't find this hard to adapt to. As for the onboard preamp, I'm happy to see it because it was needed. I'm please that they offer it at the same treet price as the U-Bass without EQ. Pissed? Not really. When you jump onboard with a new product for its first run, you should expect things to be, perhaps, not quite tweaked. I bough a Fishman outboard EQ that I usewith other basses. so I'm OK with that. I don't really expect Kala to offer a no-cost retrofit to previous U-Bass purchasers.
Lakland 55-94D, Steinberger XL-2, Rickenbacker 4001C64, Hofner Icon, Kala U Basses, Stagg EUB, Line 6 Studio 110, Genz-Benz Shuttle 6.0, TC-Electronic BG250 combo