The room is around 45 m2. My speakers go only to ~60 Hz which is for sure not low enough. To mix the bass I use headphones and the car speakers. Usually my kicks are too loud and my sub bass is too low.
For instance here the low end is wrong imo (the kick is too loud):
while here I got it right more or less imo:
The whole topic also pisses me off, because you need a shit load of absorbers to achieve anything. The treatment works well in the time domain, but to get the frequency response flat is very difficult.