Due to lots of requests, I’ve build a 64-bit version of the Tube Preamp VST plugin. It’s downloadable from the concerning page.
Unfortunately, I’m very busy at the moment, so I wasn’t able to do lots of testing or bugfixing. Hopefully, I’ll find some time to rework the algorithm in spring, when my exams are over. Until then, feel free to download the plugin and test it. Please report any bugs via email!