Hello Troels,
Last Friday (31st of March) I finally finished the build of my DTQWT’s. It was already more then a year ago since I had the box with components delivered by Janzen Audio. Last November I started with the building and had made the 21 mm Birch Plywood sawed by a furniture builder. Beside of that It was a very challenging project because it was my first speaker build project. I am also grateful to have made some little mistakes where I could learn from. I am very satisfied with the result. The speakers are now a few days in my living room and I hear already some improvements. You did a nice job with the engineering of these fabulous speakers, thanks a lot.
In the past I build some tube amplifiers myself based on the EL84 and tried them also on the DTQWT’s. To my surprise they are sounding very clear nevertheless the power of the amps are only 3 and 4 watt.  (EL84 single ended and EL84 push-pull) They sound in the mid-high levels more transparent then my Arcam A32 integrated amplifier. I also made a tube amp with a 6AS7 pushpull configuration (see photo), but unfortunately it needs some improvement and attention. It will deliver 2x 25 Watt in Class A, so that should do the job, I think.
The sound is already very clear and sometimes the bass kicks in very deep, especially with a shaman drum of other low frequency. The nice thing about the speakers is that they only let you hear what’s there. So again thank you Troels, I am very grateful for your design.
Kind regards,
Rinze