Those of us technically educated generally believe that a lot of tweaks don't have sonic effects, because it is scientifically unlikely and hasn't been proven. So we often invest our interests in things like over-engineered products. Those people who are convinced that cables sound wildly different and Shun Mook Mpingo disks are a requirement for good sound are doing what helps the illusion of stereo best for them. My own interest tends towards simulating a more realistic soundfield than exists normally with two speakers. The bottom line is to buy what makes you feel good.
Tubes often give a full bodied mid-range, and solid state usually has crisp highs.
Some want the most accurate reproduction based upon what they think live music sounds like. I personally have wavered back and forth between many of these goals, and don't have a set purpose in high fidelity. However, have an open mind and try different things, because you may learn that you enjoy what someone else does. Since our hearing is a function of the ear AND brain, it naturally follows that psychology has a good deal to do with it, i.e., perception of what sounds good. On the other hand, some like to transcend their personal biases and know that what they hear is physically accurate, as well as enjoyable.