Hello MMW,
I'm not sure where you read that, but I've just flicked through the manual for my RX-A2010. What do you mean by equalising subs, at certain frequencies? What certainly can be done is to manually adjust the frequencies (after YMPAO calibration with the supplied microphone) at which satellite speakers that are designated as "Small" cross over to the subwoofer. You can also manually adjust the levels of all speakers, including the subwoofer, if you feel that the speaker levels that the YMPAO calibration are too loud or too quiet.
(I started to write the above in response to your intial post, but got distracted and when I eventually posted it I saw that there have since been other postings back and forth.)