Here's a track that I've found to be extremely useful in diagnosis of room/speaker interaction and speaker design. It is a recording of every key of a Fazioli grand piano done by Steve McCormack. The piano player is also Steve, and he said that he tried his best to hit each key equally hard.
From Steve - "It was recorded at Soka University (where Jim Merod teaches and runs the "Jazz Monsters" concert series) several years ago. A Fazioli grand piano (a truly magnificent instrument) had been loaned for one of the concerts with Mike Garson. I recorded it to a MOTU 826HD via Firewire to my then Windows laptop. When the concert was over I waited until most of the people had left, then sat down at the piano and made this recording before teardown. Yes, it was 24/96 native, and done in stereo. The conversion to 16/44.1 was done in Wavelab, my standard at the time (these days I have superior tools from Izotope for doing up-or-down sampling)."
Just in case anyone questions Steve's recording "chops" - he was one of the recording engineers behind some of the fabulous M&K Realtime direct-to-disc albums done in the 1970's.
With a pair of well-designed loudspeakers, in a properly set-up room, each note should sound subjectively equally loud. If there is a big difference, especially from one note to the next, you have more work still to do (either in your loudspeaker design or your room set-up).