You may think this is another method, in any case, it's relative to the bass.
’Good Enough’, don’t try for Perfection, just adjust what you already like.
Document what you have to start, and results of changes. Patience!!!!
Start with test tones from a CD (not LP, something in your alignment could be slightly off)
CD, tracks 9 to 38 are 29 1/3 octave test tones
Measure at listening position, seated ear level
Sound Pressure Meter, need hole for tripod mount
Chart, copies, write things down, use Pencil. I made enlarged copies of the booklet track listing.
Adjust, how?
My speakers, 15" woofers, you do not adjust the bass, you adjust the midrange horns (2) and horn tweeter relative to the bass, with pair of built-in L-Pads, so more or less mids, then adjust the tweeter horn to the mids,
One side, other side, then both, reduce ? back and forth, take a break, until the best you can do, took me 1-1/2 days last time.
then use your ears: old ears like me, typically boost the highs some but not too much.
Use music you are very familiar with for the final by ear adjustments, i.e. Eurythmics ... Cassandra Wilson, War of the Worlds Richard Burton’s voice, Enough is Enough Streisand/Summers Duet .., Friday Night at San Francisco 3 guitarists last 2 tracks
EQUALIZER, no level controls, why not see what one can do?
31 Band, Dual Channel EQ (DBX Clone, identical)
Adjust the Equalizer using the SPL Meter, when done it has Bypass IN/OUT Switch, so you hear any detriment if any, when IN at zero, when OUT, and hear results of any adjustments. Use the meter, use your ears last.
After messing about with it, I disconnected it. Waiting for friends with younger ears to let me know what they hear.