How do you know when a stereo sounds good?

First, I have to address @aewarren's post. Unless you like to whine, Adele will never be listenable. If I didn't speak the same language as Adele and didn't interpret every song as a whine fest, perhaps I may like her. Unfortunately, short of a brain injury that is not going to happen.

@winnardt , i sort of see where @hilde45 is coming from, and perhaps it is the crux of Ted's post. Without a "reference" how do you know if your system is good or bad? And even with a reference, how do you know that the reference is good. From there, what is "good". Quite obviously one audiophiles good is another's crap. People will say "when it sounds like a live performance" ... what venue, where are you sitting, what was your mood, what was your concentration level. Even for a live recording, what is on the recording is never any more than what the recording/mixing engineer thought it should sound like with their system and their ears and brain.

I will take a different tact. Few people have the tools or knowledge, and far fewer the inclination to do the work and understand what, for them, or even in general, "sounds good". You can only "explore" what sounds good, even to you, when you can control for variables. Some of the people who have done this over time we know very well, i.e. everyone knows who Floyd Toole is, perhaps the king of "measurements" in audio, but no one questions that because the result of his measurements is targeted at what we prefer, in general, subjectively. One could say the same about Nelson Pass who intentionally makes amplifiers that are not accurate, never really claims they are except for specific aspects, and who even communicates and markets as such to suit the tastes of his customers. Then there are people behind the scenes intentionally adding distortion and even noise because they know for their target audience, in general the result will be preferred. Floyd, Nelson, and the people behind the scenes learned all this by controlling variables (which includes mood and bias).

I got a private message on my first day, suggesting a look at system pictures, as it would be eye opening. It was. I thought most hard core audiophiles would spend far more time and money on their listening space. I was wrong. How can these people know if their system sounds "good" if they don't even know what their system is capable of or what could be wrong with it?

How do I know my system sounds good?  I know the distortion of my speakers is low. I know the distortion of my electronics is low. I know the on-axis frequency response is flat. I know the off axis response is smooth and controlled and room response is close (but not exact to what Toole and others recommend). I tuned that to my liking, including too much time on acoustics and an unhappy handyman/carpenter. I suspect age may play into my preference for a more elevated high frequency response.

Does this guarantee that my system "sounds good". No. Does my many audiophile buddies saying "wow" when they hear it suggest it sounds good? Possibly.

Here is the crux, everything, including my turntable goes through DSP. I know, heresy! That means I can control everything. Want the system warmer, it is warmer. Want some nice tube distortion (also another form of warm), you got it. Want to center the image a bit, throw in some crosstalk. Want a perceived wider soundstage/concert hall, through in a touch of reverb. I still don't have that one where I want it yet. For me personally, it is normally pass-through, though I find with some music and my mood, the tube "simulation" sounds better to me. When I have friends over who are die hard tube fans, they are amazed that with a few buttons I can turn the system into something they associate with tubes. Some really like the touch of reverb, but I don't think it sounds right yet.

How do I know my system sounds good? Because I built the best "reference" I could within budget and time limits, which gave me a system I could isolate variables with which allowed me to explore what I like and which sounded good to me, but which I could adapt to others preference or my moods. There are some things I want to try to give me even more flexibility, but time is never our friend.

Less posting. More time listening to music. 

I’m a music lover first and an audiophile second. For a long time this served me well, until we bought a house and moved from a flat. Prior to that I sat near field and I was happy listening to music. After moving to a much larger space the room became a huge part of the equation.

To that end, and to the point of the OP’s questions, I initially relied on my own subjective opinion. And I knew it didn’t sound right.

I needed new cables and power cords because of the changes in my equipment location, etc. So I tackled that first.

Next I knew my cartridge was long in the tooth. As part of the upgrade, I enlisted an expert to analyze my new cart and set up my table using math, science, physics and subjective criteria.

Then we moved on to the room and the main speaker interaction. Again, I went with the same expert who deployed a scientific, data-driven approach to optimizing the room as we did with the table. Ultimately, a combination of room treatments and a distributed bass array we’re deployed to optimize the sound. (I made other changes to isolation and cable/power cords.)

Essentially, through this process which took about a year, I have seen the light in terms of combining data and measurements with the subjective to get closer than I’ve ever been to musical nirvana. (Okay "nirvana" is a leap but you get the idea.)

I now have a rock-solid system built on data--starting at the source. My toes tapping is the subjective part that tells me, Eureka, that’s what a good-to-great stereo should sound like.

But I know there is more to get out of my system.

I don't like to whine, and Adele is a great singer and extremely listenable. Good thing people can have different opinions without one having to be wrong.