Upgrading my acoustical room treatments

[ToTo Man]

Another point, it seems you picked the Scopus that corresponded to your room dimenions, and not the frequency of the biggest measured peak. Am I right? - apologies for bringing it up only now, but it dawned on me after the fact.

Yes that's correct. However...the 43Hz peak does become the biggest measured peak if I move my listening seat back towards the rear wall. The reason it looks so well-behaved in the above graphs is because my current listening position is so far away from the wall. Move 30cm closer to the wall and you can clearly hear the 43Hz mode taking over. Even with the Scopus installed, Bee Gees' Size Isn't Everything remains off limits unless I sit well away from the wall! The 53Hz peak by comparison isn't as intrusive because it has less ringing.