Mechanical noise was a good hypothesis: I turned off all fans etc and the 15 Hz peak is gone. The quite big peaks around 25 and 40 Hz remain, and they also show with the sub turned off. So the Antimode does nothing for them and I need to address them with the rme filters. It was precisely for the facility to also equalize my main speakers that I bought the ADI-2. But boy what an incomprehensible interfac.
The RME interface with the User can seem a bit complex (at first), but as you gain a bit of experience with its functions, it seems almost intuitive!
The 25hz thing? I'm not convinced that there isn't some other intrusion happening in your Tests. Vielleicht Einen Kühlshrank in der nahe?
Home Appliances create noises that our ears filter out, but noises that our Measurement Mics hear very clearly. :0
Further, I strongly urge you to attempt the Test I described to you in an earlier post. I want that Backwave attenuated as much as possible, so we can see the result. I think the answer to your situation lives there.
Curt (Sitting in the Western US Desert...)
Willem, the "Sounds" you describe regarding your Subs suggests to me that you were on occasion listening ONLY to the Subs. Yes?
The Bass will ALWAYS sound Mucky because you are only hearing fundamental tones...not the higher frequency Harmonics, etc that give a Cello, or Bass Guitar it's "pluck" and definition. Anyone that tells you that they CAN "Count the Cycles" on their Sub alone is...well...Full of Sh...t.