Some speakers can be adjusted to fit a given room to some degree, thereafter you can fine tune position to perfection . I have different crossover settings for different room dimensions, room placement and seating distance in the passive crossover. Additionally the active crossover for the sub towers can be set for phase, gain and bass bump/dips. I am sure the Goebbels speakers can too.
I agree that DIY can go quite a bit further than just small speakers tweaks.
But, to get the most out of DIY, it does required work. But as said before, I really think a competent DIY audio builder has a big advantage compared to the buyer of a commercial device: it is much easier to tweak and adjust them yourself. Not to compensate weaknesses, but to tweak the sound to suit your taste, suit the room, experiment and make improvements, improve capacitors, resistors, power filtering, adjust amplifier bias current, etc.
My speakers for an example: I have not designed them, but I have tweaked and tuned at least as follows:
- adjusted the height and the angle of the speaker also in the vertical axis (a little lower at the back than at the front)
- tried different spikes, (DIY) damping feet - and finally made a Boenicke Swing Base style solution for both the bass units, separately for the tweeters and also for the external crossovers.
- made a small adjustment to the crossover
- made the crossovers external
- adjusted the length of the reflex tubes so that it would sound good/balanced in my room and to my taste
- tried different internal cables
- tried the effects of the different internal damping material (amount / location / tightness)
- made my own speaker connectors, where the wires are directly connected to each other, but still tightly compressed
And also, practically all my other devices have also been tweaked in some way - also made my own signal and speaker cables, etc. (which are better than the well known brand cables I had)
Doing it yourself takes a lot of time, and of course it requires some knowledge (one can learn), some curiosity and hand skills. One also needs the willingness and time to experiment and listen a lot. Sometimes the changes works, sometimes they don’t - but you always learn more.
I think that in the DIY world you can achieve a level of sound and balance that you may not otherwise afford - and that can be difficult to achieve even with expensive gear, because you are always tied to the manufacturer's vision of the device's sound and balance.