Sound quality of music system depends on several factors. Loudspeakers are obviously one of the key components which affect the sound quality. In fact, almost all of the distortion is caused by loudspeakers. People don’t realize that because speakers typically don’t show distortion rating. However, the fact is that loudspeakers have distortion of close to 5% when driven to their maximum wattage.
Audio amplifiers also have distortion but usually a lot less than 5%. In order to improve sound quality, I recommend to purchase loudspeakers which are designed for larger wattage then you actually require. I also recommend the same for audio amplifiers. The reason for this is that both loudspeakers and audio amplifiers show distortion to increase rapidly when getting close to their maximum. By staying well away from the maximum rating, you can stay within a fairly linear area and thus minimize distortion.
Also, when you drive loudspeakers fairly hard, vibrations can occur which can affect the sound. Vibrations can usually be minimized by lowering the wattage that is used to drive speakers. Also, by selecting a location for the speakers which is sturdy and soft can also minimize the effects of vibration.
When placing loudspeakers, it is important to pay attention to the surroundings. Surroundings can affect sound waves quite a bit. I would usually recommend to make sure that the distance between the speaker and any walls which can potentially reflect sound waves is at least 3 feet. Also, I would typically place speaker at least 6 feet above ground. However, in many surroundings, this is not possible. Therefore, sound will be affected by reflections on your floor. However, you can use some carpeting and other non-reflective material to minimize this effect.
Interconnecting cables can also have a detrimental effect on sound. Lose audio connections are one of the primary reasons for equipment to fail. Sound can be degraded if any particular connector does not make proper contact.
The best remedy is to purchase some high-quality audio interconnecting cables. Also, by using optical cables you can minimize the effect of interference that might potentially couple into the signal. I would generally recommend to minimize the length of a cable run in particular speaker cables.