A good audio gear collection is something that spans a variety of criteria. There's no set unit of measurement that defines what will make for a comfortable listening experience. Yet, there are some key factors that can be analysed and compared to estimate the overall usability of your device. By doing this, you're bound to get a clearer picture on whether or not a speaker is worth purchasing.
Frequency Response
The first factor worth highlighting is the frequency response. In a nutshell, this term measures the range of sounds that can be reproduced by your speakers. A regular hearing range for human ears tends to sit between 20 - 20,000 Hz. Thankfully, most speakers are capable of covering that range as they tend to measure between 45 - 20,000 Hz. Yet, the frequency response doesn't paint the full picture. Even when a speaker is capable of hitting certain frequencies, the quality of its sound may be lacking.
As a speaker owner, it may be tempting to only use frequency response as your main factor for purchase. This shouldn't be your goal. On that note, a good rule of thumb is to prioritize speakers with a smoother frequency response rather than one with high variations.
Phase
When you have a home theater setup or a connection involving multiple speakers, it is imperative to ensure that your sound waves are correctly set up. The "phase" of your speakers basically entails how the sound is in sync across the board. In other words, you're not meant to be hearing left side audio with the right side speakers and vice versa.
When your speakers are out of phase, it can hurt your listening experience. The lack of a coherent phase is usually due to poor wiring with positive side/negative side connections located in the wrong place.
Crossover
When you own a speaker, having a crossover is really helpful with driving the sound into the right frequencies. To put it simply, speakers have a crossover network within and this helps the speaker filter certain frequencies into different ranges. A good crossover is nice as it improves the reproduction of frequencies in your audio.
Terminals
On a speaker, terminals are a color coded module that helps with the frequency ranges by connecting your wires to the drivers. Mid and high frequency drivers have their terminal, and low frequency drivers have theirs as well.
Ensure you're well connected by checking for the positive and negative terminals while setting up your speaker.
Sensitivity
When you're buying a pair of speakers, the sensitivity is an important factor to look for. This is thanks to the fact that it determines how high of a volume your amplifier needs before it can work best. It also implies how loud your speakers can get when fed certain amounts of electrical input.
Impedance
The impedance of a speaker is basically the sort of resistance an amplifier encounters when driving a speaker. It is measured in ohms and it is mainly based on the frequency of a speaker.