More Gear Days, I'm thinking Octobers will be devoted to it, but we'll see. This post is about determining how good a piece of output gear (headphones/speakers) is. There are plenty of articles out there on this topic, but I'd like to put it in my words and at the same time give you some other viewpoints in the form of other articles.
The first thing you have to consider is why even buy different headphones or speakers? Sound is sound right and no matter how much you spend the sound quality won't be very different? Well in my opinion, everyone can tell the difference between cheap headphones and more expensive ones. In most circumstances and uses it might not be horribly important to you but I think that everyone who can hear can tell the differences between one pair of headphones or speakers and another.
So let's get to it. First off is the form of your output. Obviously things sound different on speakers than on headphones. Additionally, how those are built and their forms have an effect on the sound produced, see the previous post on different kinds of headphones. In this space, headphones are a bit more diverse, but there are distinct differences in speakers as well. For instance, a quad system or a 5.1 surround system has different spacial effect that a simple 2.0 system. By the way, 5.1 means 5 'tweeters' and a sub woofer, if you were curious or were not aware. They make for great home theater systems due to their ability to create sounds that can take up a space with really good positional sound, namely you can hear sounds coming from 5 directions. The spatial effect is sometimes called 'panning', more commonly so in 2 channel systems and is actually really important in determining sub par equipment from great equipment. Great equipment accurately represents space instead of shoving it all to the center or in strange places. It's also a good way to tell when equipment is going bad since the center of the sound might shift to the left or right which is likely a problem with your gear.