How to do speaker correction on a MacBook Pro Retina
Late edit:
Since writing this, Rogue Amoeba have released a simpler &amp; cheaper app specifically to tailor output rather than provide full internal audio routing &amp; recording - SoundSource. You can set up your EQ or whatever as a global or on a per-app basis, making it very flexible.

I wrote this before checking all the proposed apps in the OP; my issue with these kind of things usually is that I tend to avoid the &quot;we can do it all for you&quot; apps, like Boom &amp; Bongiovi; because I always think, &quot;How can you do all that for me? You can't hear my speakers!&quot;.
eqMac2 does look like a simpler version of what I'm already doing on the first machine example below... for free. You still need ears, or an analyser, but the investment could become 'merely time' rather than actual cost.

Potentially what you could do if you have access to a smart phone is download a free Spectrum Analyser &amp; find a white noise sample or generator online* then use the EQ to flatten the perceived EQ curve as the phone hears it.
You could do this with Soundflower &amp; a graphic EQ too, or potentially with eqMac2 - for free.
There's a slicker solution than Soundflower, but it's far from free - Audio Hijack - which I use to tame the audio on several machines here, for slightly different purposes.
I get the feeling it won't be what you're looking for, but it's quick enough to throw in here &amp; see if any future Googlers might like it. I do seem to come across as a one-man campaign for this app, but it's just that it's the best I've found for many similar purposes. I have no affiliation whatsoever.
If someone can find a free equivalent, I'm all ears - quite literally ;)
One cool thing, though is you can set timers for it - so to get it to be 'always on' I set it for 23h 59m of every day &amp; let that spare minute be when I'm bound to be asleep.

On one machine, I use it to compensate for cheap external speakers with an odd EQ curve. I simply send all audio through it to flatten the perceived EQ curve.

On the other machine, I use it to compensate for the very high dynamic range whilst watching movies - which are piped through to my powerful 5.1 system, capable of offending the most tolerant neighbour. I use it to simply keep things within a more acceptable range to suit me &amp; my neighbours...

Both these setups just use Apple's built-in AU plugins.
Unfortunately, there is no automatic setting for either of these setups. I do it by ear - but I'm a pro sound engineer &amp; I trust my ears to get it at least close enough to be acceptable to any listener.
*No affiliation, just one I've used before.