Equalizer in a Hi Fi system

@tattooedtrackman , if you make such a change, it may prove very exciting and gratifying for you. 
 

@mijostyn , thanks for your comments. Your knowledge base in the digital realm clearly goes beyond mine. I just know what sounds great and what doesn’t and have hit upon an equation that works for me. I have had many say my approach sounds seriously good, so I guess I’d simply say just be open minded is all. My speakers are old. They are Martin Logan Montage dipoles. They are entry level hi fi but were favorably reviewed in Stereophile. And I’ve heard them on seriously great amplification at Audible Images in Melbourne compared directly against 12,000 dollar Sonus Faber Olympica speakers. Ed the dealer there and myself were shocked that the didn’t lag very far behind. But they did. And when I update the speakers I will really have a killer sound. Honestly, the pro studio CO has upped my game so much that I simply have been complacent in replacing them as the SQ is already phenomenal. 

Years ago, I came across the term "corrective technologies". At the time, it was used in the context of home automation, but the presenter added that we apply "corrective technologies" to many things. Auto mechanics fix things that are poorly engineered, or just worn out. Doctors correct things in the body that are not working as they should. ER rooms fix things that can be the result of very poor judgement (possibly by others). Yes, there are hearing aids for hearing loss. And equalizers for frequency abnormalities.

To use medical terms, there are "acute" and "chronic" sonic issues with our systems. Acute issues are there temporarily. Chronic issues are 24/7, always present, reminding us that our system is not quite perfect -- yet. BOTH of these conditions can be helped with the right solution. But getting us to the finish line may require slightly different "corrective technologies."

Solutions can be multi-faceted in that a "one and done" may not get us all the way there There’s also the aspect of applying the right tool/technology to the problem. We don’t call the demolition crew to tear down a structure when an Kitchen cabinet upgrade is the desired outcome.

Many here have suggested working with the room, first. I think this is a valuable consideration. Maybe the FIRST consideration. IF the room is an issue, room correction will help tremendously with those "chronic" problems. But, also calm the effect of those "acute" issues (recordings?) thus minimizing their impact. Perhaps to the degree where you "take the exit" and you’ve reached an acceptable performance level. I’d also look at out sonic "warts" in the system such as the components themselves, cabling, power delivery, etc. I fully understand this could cause a case of "mission creep" where a perceived simple one component solution could grow expoentially. But, if you find the solution is in one of the above, then it is evidence that you found the right solution, as opposed to to putting a bandaide on a problem, thus masking inherent problems in the system/room.

So, if all the above points to the direction of an EQ, I would go with separate L/R controls as some have suggested here. Remotes controls are cool, and convenient and allow you to do instantaneous comparisons from the "money seat". (The seat where the person with the money sits.)

There was some mention of tone/level controls in vintage speakers. I am a proponent of conserving the looks and function of vintage gear. I also like to squeeze as much performance as I can out of these vintage pieces. Our practice is to bypass tone controls and replace them with high quality resistors, experimenting with values until we get a flat measured response (and, extended listening tests). These, invariably will provide less dynamic compression, improved detail and focus, and wider/deeper soundstage over the factory tone controls.  It’s nice that the manufacturers of the day thought through the problem of their product being placed in a variety of environments and allowing some user correction (or, personal taste). Modern speakers have gotten away from this for a reason(s). We don’t see speaker fuses on receivers these days, either.

There are no right or wrong answers to the OPs question. Just a matter of the application of "corrective technologies" to provide the best sonic bang for the buck;.

It’s funny. Whenever I rent a car I observe people’s tonal preferences on mid fi car systems by seeing where the last driver set the bass and treble. It’s almost always the case that both are jacked way up or maxed out. Hell, as a youth I did this with my old school stereos. You might easily say these are inferior systems and you would be right. Be there are lessons to be learned in the observation made. Why do people like smiley face EQ on mid fi systems?  The answer is they are trying to improve perceived fidelity or realism with the limited stereo and tools they have. So adding bass gives more depth and weight to the sound. Fair game. Adding treble is an attempt to give more sense of air and space between instruments. Another fair attempt with the limited situation. So on cheaper systems smiley faced EQ is an attempt to get closer to hi fi. But it’s merely an approximation,  not as good. 
now, move on to the fully formed images of instruments in a high fidelity system. Rich full bass. Deep wet but fast note saturation. Great height depth width of soundstage. Snappy, accurate transient response. Now to that base ‘painting’ if you will you then add to your average recording REAL air and space with a studio EQ analog air band and a touch more well textured controlled but detailed bass bell or shelf (your preference). Now you’re really cooking!

The magic lies in adding a judicious amount of high end studio EQ to an already very hi fi mids base. The combination is absolutely addicting!  You are essentially continuing the mastering needs of that recording specific to YOUR system on the post production playback side. A true case for the cello palette Levinson theory in the article i cited much earlier in the thread. 
I almost liken all of this to cooking up a beautifully palatable recipe. That’s why I call it special sauce. It’s uber hi fi through ‘cheating’, I often joke!  Lotta bang for the buck here!

I usually bump mids on CO half dot. More of a W curve. Only slight mids bump. Done right, the whole thing sounds bigger richer fuller while retaining to my ear all the hi fi qualities of the unaltered base recording. All 3 of mids lows highs sound bigger and better in every respect post EQ. Going back and forth I honest to God cannot hear a lost hi fi quality or characteristic at all. Only better. Timbre of all instruments stay natural too.