Measurements of stereo components have a place and a purpose. The manufactures must use measurements to validate their product and maintain quality control. And it is certainly good that we have reviewers that make detailed measurements to verify manufacturer’s claims- legitimate reviewers that publish peer reviewed results and will first contact a manufacturer if something measures amiss rather than play the, "gotcha" game. These reviewers fill a critical need.
It’s easy to get caught up with some specs on a sheet of paper for a stereo component. After all, some things are important for system matching such as power output, impedance input/output, Signal to Noise, Damping factor, etc. Matching a cartridge to a tonearm, for example, must start with effective mass, compliance, output levels, impedance, etc. Beyond these system matching criteria listening becomes the most critical factor. Even setting up a tonearm requires listening to get the VTA, tracking force and anti-skate dialed in. I’d love to own one of those $5000 meters to dial in cartridge azimuth. Alas, I must rely on my ears for that too beyond the critical inspection with the stylus sitting on a mirror.
The most important measurements we can make as end users is our listening room. Beyond a mid-fi system, the listening room becomes the most critical stereo component. The room volume and shape has an impact on frequency response, reverb, and system resolution. The walls, ceiling and floors can respond to the music just like a speaker cabinet and smear the sound causing less focused imaging, loss of resolution, muddy bass and harsh highs. Ambient noise levels can also compromise our efforts to get that hifi sound. Ugh! Is it all hopeless? Not quite, but some effort is required.
Since most of us do not have the resources or cannot reinforce walls, ceiling and floors to make them as stiff as an all aluminum speaker cabinet, we can add isolation and dampening to components to improve the state of the listening room. Some DYI tools that I like to use these days are the FFT analyzer phone app and vibration app. Yes, I know these tools are not calibrated and not accurate enough to publish data, but they are good for reference to see what changes have been made while experimenting with dampening and isolation materials. Ultimately the final judgment must come from your ears but the apps help to understand how the changes we make are affecting the room. Computer programs are also available to calculate ideal speaker placement for a given room. These programs can be a starting point.
I’d say as a rule of thumb; once a system investment is greater than $20k it is important to start to have the room decor fit the stereo instead of the stereo fitting into the room decor. Beyond $50k or so in a stereo system, it is best to have a dedicated listening room with acoustical treatments that fit the room for improved frequency response and resolution. The room layout should be designed either with a good computer program or an experienced audio expert. Of course, trial and error for someone willing to learn is always an option.
Beyond $150k for a stereo system it should be in a purpose built listening room to take full advantage of this level of gear. This is a room with reinforced walls, treatments and dimensions to fit the system contained within. A room like this must be designed by an acoustics engineer.
I had a purpose built room a few decades ago that I designed and built myself. I had only a modest stereo system but it sounded amazing in that room. After I gave up that purpose built room due to relocation, I spent a lot of money on gear to get back to that level of sound.
I know some people feel that stereo gear should perform optimally in any room without the need for "band aid" room treatments. And most systems can sound pretty decent without all that. It’s that last 5%, that goose bump inducing sound that we are trying to achieve.