Next upgrade?

@sounasega ...Hmmm, I see your point...and what your concern may be.
If one doesn't discern an issue or a fault, it could cause a 'pause' as to 'what's Next to pursue and where to go with it all'....

Having 'grown up' (which some may argue That point *L*) with everything from a 'record player w/detachable speakers' to various collections of various components that varied from questionable quality to some 'nice' stuff....and listening to parents' polka music and Crosby, Sinatra. 'show tunes'....and Spike Jones for grins Then.

Coming of age in the '60s'>'70s' in SoCA, hairline buzzed, everything from Mitch Miller 'sing-alongs', jazz of the time, 'bubblegum' music, surf tunes, Zappa, The Fugs, symphonic, classical, at all manner of dB levels on various types of equipment, 'live' piano, outdoor and indoor concerts of everything from Bluegrass through The Dead to 'parody spoofs' of classical with PDQ Bach.... Lately, EDM, Fat Boy Slim, and 'acceptable/accessible' rapping....*sigh*

Most would say my taste is Toast. *LOL* 
That, and creating a 'run-on' sentence that basically verifies that.... ;)

I've developed for my own a-muse-ment an opinion of How and in what fashion and means employed to 'get There'.

hilde45 is correct, REW is not a way to Listen with; it's more of a testing app to determine how your system responds, source through speakers in the space you listen within.  A 'this is what Is' tool, the baseline of the total employed.

Granted, the laptop/desktop employed with a calibrated mic and the audio program/board onboard will 'have its' own input' as to the results you get.
But, it's a 'jumping off point' that can weigh in on wtf is going on.

I like basically to listen 'flat response' in the space; an inline eq, whether through my puter or any one (or more) of outboard eq's.
I've 2 programs and 4 outboard 'stand-alones', + 3 versions of outboard crossovers on hand.  But, when not Listening for just the sheer enjoyment of what I'm playing to enjoy self, I'm diy-ing omni speakers of a favorite variety and trying to keep a handle on what they're doing vs. how I've made them do it.

*G* There's more versions of 'esoterica' before one tweeks with cables, fuses, and elevating the speaker cables than you can shake a tonearm at....;) *L*

To shorten a long riff on it all....I attempt to make it sound like IRL, 'Live'.

As I remember it to be. as I think it should or can strive to be.

Your quest is just as valid as mine....or anyone else's in that matter.

Enjoy it, and enjoy where you are...'Be Here Now', as we used to say. *S*

Good luck, happy trails 'n trials. J

@diezahlen  is correct. This is a must before an upgrade.

@sounasega 

Problem is that I don’t know what my end goal is because I don’t have any memory of other systems I have heard in past. I can only use my current system as reference and discern why and how I like the results of changes on the same system. 

In REW, you're seeking a curve that doesn't go too much above or below 6db (to pick a very audible amount) of your input signal db (say 80db).

If it's 6db or more below, you are missing actual notes. Adjust the room, speakers, etc. to get them back in and you will here the presence of notes and other auditory phenomena that you didn't before. You don't need memory of another system to be able to say, e.g., "Hey, there's a tambourine at back left." Or, getting rid of a peak at 80 hz, you might say, "Ah, the strings and fretting of the bass are now clear; before, it was just a puff of bass-sound." 

Does that get you started? 

@hilde45 thanks a lot, yes this is great to get going. Essentially you want a flat frequesncy reponse at the point of listening. I like working towards that reference rather than my not super trained/experienced hear. This is is going to be a fun project :-)