What exactly is a speaker box sound?

The best way to explain this is with your EARS.  Go to a high-end shop.  Listen to the same source--one you believe you know well--on any and every box or horn or whatever speaker they have.

THEN, listen to the same source on Magneplaner speakers.  If you cannot tell the difference, buy the speakers you like best.  If you can, you have learned what I did in the 1970's.  ALL box speakers change the sound of the source.  Some may like that, some may not.  Maggies deliver whatever you send them.  Once again, some may like that, some may not.  As for pure electrostatic speakers, give them about 30 minutes or so and you will understand the term "listening fatigue."

Cheers!

@roxy54 

Exactly why I suggested to the OP that he listen to EVERYTHING and buy what HE likes.  While we may disagree on what Maggies "add" or "sound like" in a given situation, I, PERSONALLY, have never heard a more accurate reproduction of the source material when the ROOM is right and the HW is top-quality (ARC in my case).

My shop sold over 20 brands of speakers, so I definitely understand that people have different tastes.  My point to the OP was to listen to as many DIFFERENT things as possible before making a buying decision.

Cheers!

@erik_squires 

I suppose you are right, but his point was asking about box speakers.

ALL of them distort the source material.  How much is up to HIM to hear.

Period.

By the way, do you find it interesting that most "high-end" makers of box speakers have chosen a "tall" form factor ever since the late 1970's or so?  I WONDER where they got THAT idea?  I will have to ponder that one for a while, I guess...

Cheers!

@twoleftears 

Well, we shant have it!  Heresy, indeed!  Off with their, uh, feet!

@roxy54 

Like I posted, everyone has their own opinions.  Buy what YOU like.

@secretguy 

Thank-you!  Everyone likes to be agreed with.  I had the good fortune to LISTEN to many brands of gear played through many brands of speakers when I had my shop.  We also had real musical instruments present, and were able to compare them to (processed) recorded sound.

I come by my OPINIONS through many hours of listening to many, many "high-end" products in my shop.  Whether others find the combo I believe to be most accurate to their liking is why there are about 500 manufacturers of home audio "stuff" around at any given time.  Makes it all fun, I guess...

Cheers!