the big one: how do you choose speakers? By what features, data?

@grislybutter These things do not necessarily show up in specs. They are usually design elements that produce a certain effect. Some of it is personal and a matter of experience. For instance, I could care less what a speaker looks like as long as it is well constructed. I want a speaker with sharply limited dispersion, no more than 45 degrees above 250 Hz. Only dipoles and horns meet this requirement. The purpose is to minimize room interaction. I prefer the larger, more realistic sound stage of a line source but in order to work well it has to cover the entire spectrum from 10 Hz to 20 kHz or beyond. This now limits me to very large dipoles. At one point Magneplanar was thinking of making an 8 foot 20.7. The marketing department talked them out of it! In order for a line source to function down to 10 Hz it has either got to be 60 feet tall or run from floor to ceiling, all the way from floor to ceiling. The two most common ceiling sizes are 8 and 9 feet which is why Sound Labs makes 8 and 9 foot speakers. You could easily make ribbons or planar magnetics do this but to my knowledge none do! Fine by me as I prefer ESLs anyway as they can be run without any crossovers to great advantage, excepting one to the subwoofers which I think are mandatory for these speakers to sound their best. As a matter of fact I purchased my Sound Labs without ever having heard or seen them. By design I knew exactly what they are capable of. I had 8 foot Acoustats for decades, a very similar speaker. 

@yxcbandit  The problem with trusting ones own ears is that most of us do not have ears we can trust. How you hear a system depends entirely on your experience listening to a multitude of systems. You cannot know what a system is capable of until you hear it. I built my first amplifier in 1967, a Dynakit Stereo 70. I had no idea how well a system could image until I heard the system of a high school teacher in Miami, FL in 1980. That system had been my target for some 35 years until I managed to build a system that functioned above that level. A large part of it was the room not his system. Back then people were just beginning to deal with room acoustics in residential settings. 

Another problem is your ears can not tell you what to do proactively. My ears do not tell me what equipment to buy. They do tell me whether or not I have that equipment set up correctly as they have that reference built in. 

The key is to gain as much experience as possible listening to other systems. This is not easy. I was fortunate in that I paid my way through school setting up HiFi systems for very wealthy people and worked with the top high end dealer in the area. I got to hear a lot of systems in more intimate environments. It is unfortunate that shows do not work well for this and you have to be deceptive with dealers. In order to get their best service you have to make them think you are qualified (read wealthy) and ready to spend a fortune. Wear gold jewelry and drive up in a 911.

In short, your ears can tell you what is acceptable to you. They can not distinguish  what a system is capable of without having heard it.  

@mijostyn design elements are usually on the spec list but of course it varies. EVERY brand publishes a different set of data

and of course my knowledge is about 3% of yours, my selection criteria is way more basic.

@grislybutter Sometimes too much information can hurt you, especially in this audiophile hobby. 

If you constantly watch speaker reviews, then you'll constantly be fed the same information. This information shall influence your decision more than you'd like to admit. 

Case and point: the Klipsch RP600M was the best thing since sliced bread back in 2019. It got all of the awards from the press and the online community hyped it up to insane levels. I sort of fell into the trap, only because I purchased them without audition at 50% off. The deal was "too good to pass". When I set them up I was underwhelmed. My dad's Q Acoustics 3020 just sound better in every metric (vocal clarity, bass, smoother highs...). 

It's clear that "you get what you pay for". Honestly, most speakers in the entry-level from big brands like Klipsch, B&W, Focal or Triangle perform similarly. It's just that subjectively some brands sound a lot worse to me than others (Klipsch grrrr...). 

Nothing beats a real audition, and with multiple speakers of different brands in the same room. I was honestly shocked how similar the KEF LS50 Meta Wireless and KEF LS60 sounded. The KEF LS60 just have more bass. 

You gotta jump the shark. Go to audition stuff. 

@grislybutter , Marketing is the fine art of lying and numbers can be misleading. Learn about the physics of loudspeakers, crossovers and drivers. Learn about acoustics. Everyone is worried about ears. You need to use your eyes first. This is so and so a speaker, now how does so and so a speaker sound? People who know what they are doing can tell in a very general way how a speaker is going to react to the environment just by looking at them. This interaction between your speakers and the room they are in is the single most important determinant of sound quality.

Anyone can make a speaker that sounds good, but making a speaker that can image is a whole other problem and much more difficult. The Bose 901 is a great example of a speaker that many people love but it is the worst imaging speaker on the market, even worse than Tektons. The reason modern enclosed loudspeakers like Wilsons and Magicos are so expensive is that in order to make that kind of speaker work well you have to make perfectly silent enclosures and very complicated crossovers aside from using great drivers. 

@yxcbandit , Very good point about controlled dispersion and very true. The wall behind my SLs is covered with 4" acoustic tile. However, the best way to go about this is to measure first to see what your speakers and room are doing. Trusting your ears is a mistake if they have no reference. People who are use to bright loudspeakers will think speakers with a flat response sound dull. Learn what flat sounds like and then adjust the system to your taste. My system runs flat from 100 Hz to 20 kHz and the gets boosted at 6 dB/oct from 100 Hz down to 18 Hz. This gives the sensation of a live performance at more sane listening levels. Flat is the reference. With the newest digital preamp processors you have perfect control over all of this and you get a measurement Mic with the unit. For $300 you can get a wonderful USB mic and measurement program. Measure first then adjust to taste.

Because I know what flat sounds like I can tell what a system is doing in loose terms. I will never be as accurate as a calibrated microphone. Nobody will.

I have also seen some very silly acoustic treatments. Find your first reflections and place absorption there floor to ceiling. The first reflection pattern is not straight. It is the cross section of a sphere. Absorption needs to cover this entire pattern for standard dynamic speakers. People with dipoles only need to treat the wall behind the speaker. Why?