Just what is essential?

In Sunday's post I asked what your favorite tweaks are. Lots of great answer coming in and we shall discuss some of the more noteworthy of them. In the meantime, I would ask the question of what is essential? What constitutes a tweak, and what has come to be required? Some tweaks are so pervasive they become institutionalized as a part of the landscape. Stereo itself might qualify. After all, the switch from mono to stereo started out as a tweak, enjoyed by only a handful at the time. If stereo is now institutionalized what of speaker placement? Is it a tweak or a necessity? Has setup become so ingrained in us that we no longer view it as a tweak? I can certainly remember back to the days of mono systems where speaker placement was decided out of convenience, not sound quality considerations. We could even go so far as to ask about separates themselves. Are separates a tweak or essential? After all, music comes out of a clock radio too. In my world there are a certain essential group of components required to setup a sound system that meets a minimum expectation. And I think this is where we'll start looking for essentials. What's your expectations in a music system? Tomorrow we'll look at defining expectations and then the essentials needed to realize them.