Hi everyone new here and forms in general.
My question is a simple and yet vastly complicated one. Should you eq using the Fletcher-Munson Chart or should you RTA Flat in order to get a flat response.
First of let me say that I am more of a car audio person rather than home and headphones so most if not all my experience is going to come from that area.
I’ve spent a good amount of time and money in my car audio (Specs at the bottom) and as anyone who has should know you are never done tuning or done in general 
but I digress. I got to a good point where I liked what I had done to the eq and everything and I know that I am not the only one who likes it but then I came across the Fletcher-Munson Chart and decided that I would tune the car to that. I picked a point on the radio at 28 as this is where I know if I run a test tone on the subs they don’t change tones, until 29, whereas I would normally listen at 32 and have the bass up a fair bit being a balance of audiofile and bass head. I know my system lacks a at 125hz area so tuning was difficult but managed to get it close to he line. Me and my brother (who ismore towards audiofile than I am) found it to be dull or dark but we noticed that the violins in “We Shall Never Surrender by Clocks & Clouds” were more dynamic as in you could here the notes change better than the original way I set things up. From there we did a blend of the two eq’s and later that night after letting the ears rest in lisened to my music and I was noticing how things sounded more pronounced, like the instruments and sounds had new life to them and the sound stage (as far as left to right on the dash) was more pronounced to the point where I’m like wow, some songs even has parts that feel like your head is surrounded a bit. There are also parts where you can clearly hear one instrument in the left area and the other in the right area with no mesh inbetween like I normally feel there is.
All this and yet (and now don’t get me wrong I like the way it sounds) but all this being and I still feel like at times I don’t like it and I don’t understand why that is. It definitely can very from song to song but even then I can’t seem to shake this feeling some times.
Is it really that different that I’m not used to it? Is it the fact that everything is more tailored to the 125hz problem I have given the overall listening volume is less now? Am I going about this completely wrong by using the Fletcher-Munson Chart? ((Should I get a RTA and use it it get flat?) If not what’s an RTA good for then?))
Any and all information is welcomed no matter how complicated or technical. I’m here to learn first and foremost. That being said try to explain things simple.
Car Specs
1 inch silk tweeters from Skar Audio 120 rms pair (on dash with both facing me)
Kicker 43CSS694 component 6x9’s front in door at 60 xover
(The above is using the kicker crossover at 4k and not using the kicker tweeters) (the par is equal distance to my ears)
Skar RP150.4 AB amplifier front channel only
No rear door
2 Sdr 18’s in a Infinite Baffle with approximately 13 cubic feet trunk room
Skar RP1500.1 D at 4 ohm at 60hz xover
Kenwood Excelon KDC-X702 (time aligned to the center at the manual gear shift)
AGM battery under hood with 72 amp hr
0 awg ofc wire back to 4 awg split to 4 ferad cap for each amp
Thank for reading and feel free to respond even if this post is dead if you feel like you have something to add.