I consider it irresponsible NOT to provide level controls.
Almost ALL Vintage Speakers, Electro-Voice, Klipsch, Altec Lansing, Acoustic Research .... came with level controls (L-Pads)
Mono era: started with single speaker in a space, with level controls
Stereo, ADDED a second speaker with level controls (and ADDED a 2nd amp, thus pair of mono-blocks)
The speaker(s) knew not what space/room they would play in. Later they might be moved, used in a different space. An owner's preference (perhaps a need due to hearing issues) could be addressed.
People bought speaker(s), or speaker kits (with level controls). put them in a space, located where they fit/looked good/wife liked. Then adjust the levels for a darn good sound in that space.
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Recording technics; manufacturing; design methods, everything now stereo led to starting with Stereo Pairs of speakers and all the refinements since the late 50's.
Many makers started eliminating level controls, thus no way to adjust them to your particular space.
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My main system is custom enclosures with electro-voice components (horn tweeter/horn mid/15" woofer), each with a Pair of Level Controls. You first adjust the mid horn relative to the un-adjustable woofer; then you adjust the tweeter horn to the mid.
In the old days I did it by ear, with or without a friends help. Now, sound pressure meter/tripod/seated ear height and use test tracks of single tones. My McIntosh Mode Switch helps with refining results for the best frequency balance and stereo balance needed to produce excellent imaging. Amazing when you get it right.
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My office, a pair of vintage AR-2ax, that came with level controls for cone tweeter and cone mid relative to cone woofer. One speaker gets a boost by an adjacent wall, the other does not. I was able to adjust them, so that I get very good sound balance and imaging at my monitor/desk chair which are centered on the speakers.
Like the old days: did it by ear, sounds darn good!