Well Florian, that was my thought too, but now I still do not know if it is worth buying a A-120. I already have the following filters in my system: A-101-1 / 105 / 106-1 / 106-5 / 106-6 / 108 / 122 / 124 / 127. As the A-108 is also a ladder filter it might be stupid to add a A-120 to my system. What do you think? Cheers & tia, Danny