You've probably heard or read somewhere someone saying that home audio listening is purely a subjective experience. I disagree. Listening can be quite objective.
When listening simply for the joy of listening, there's no need to consider whether the experience is "objective" or "subjective." The terms are irrelevant; the music is simply what it is.
When auditioning a system or component, however, discerning the various qualities of the music is where the controversy arises. I believe the auditioning experience is almost entirely an objective endeavor. What you hear is what you hear, plain and simple. If you hear less noise in the background, that's a concrete observation. In science, variable outcomes are often distinguished strictly by visual observation--why can't audio parameters be determined objectively by aural observation? I believe they can.
Besides background noise, nearly every audible parameter of music can be assessed objectively. If you hear too much sibilance (spitting of "s" and "ch" sounds), and after making an adjustment to your system you hear less sibilance, you've heard a discrete difference. Likewise with deep, linear bass extension compared to a bloopy or muddy bass. If a cymbal crash is brass, not tin. If instruments are focused in defined spaces, not just a blur. These are concrete evaluations where differences can be definitely ascertained.
Even a vague, hard-to-put-your-finger-on-it assessment can be objective. For example, suppose that after listening to system "A" for a while, you feel bored, uninvolved with the music. You really can't detect any difference with system "B," yet after a while you find system "B" more engrossing, you tap your foot to the music, you want to keep listening. This observation is real. System "B" is more musical and enjoyable to you. You don't have to take a frequency-spectrum analysis to validate your experience. (If you've done much auditioning, you've undoubtedly heard profound differences between components with virtually identical measurements.)
While many aspects of critical listening can be objective, the "subjective" comes into play with evaluation of what you have heard. A certain difference or improvement may to one person be insignificant or subtle; to another, dynamic and exciting.
Personal taste and preferences are, of course, also along the lines of subjectivity. Two people might hear the same differences between two systems and each have a different preference for what they like.
While seeking a higher degree of sonic perfection, there is no single "perfect" sound whereby anything else is "wrong." A vast array of acoustic and other variables provides a broad pallette for music.
Superb musical reproduction allows you to be virtually involved with the originally recorded event and to enjoy that experience in your own listening environment. Whether it be objective or subjective really doesn't matter. Ultimately, all that matters is the music.
SteveHerbie's Audio Lab