Hi all, i got some good news!

I let over 10 people listen to the speakers, and none(!) of them were disappointed.

Includes drummers which usually have high end headphones of the same price-tag (like €150+) were impressed as well.
Also a local opera singer was pleased by the sound.
Even let a local hifi-guy listen to them, and he was pleased with the warmth, and he agrees with me: still a little too much high notes coming out of them.

Luckily this is a easy issue, just need to update the filtering part.

The speakers can produce nice sound to below 30HZ (if using < 30wrms because of speaker excursion reasons).
On the rated power of 50Wrms it can go as low as about 38HZ.

Also, i calculated the wood-cost of a pair of speakers, and both will fit in one sheet of 244*122CM if done right. Also saves some wood for internal bracing if desired :)

since i got some of the €150 budget left (about €20), i might apply some more dampening to the both speakers.