The question of “Do I need to install an audio interface if my computer already has a sound card?” may be easy to answer in the affirmative, but not in the most economical way. If your sound card has a microphone as well as an audio interface, then no, audio interface will not affect sound quality.
For those who just want to listen to music without any other distracting sounds, yes, you do not have to install an audio interface. Audio interface is nothing more than a cable that is used to send audio data from a digital input device (the device that generates sound) to an audio output device. It is very much like the physical interface you find in computers which allows you to turn a PC into a music or sound card. In the past, the only way to get sound card to work was by purchasing a dedicated sound card. Nowadays however, you can use an audio interface with almost any computer.
Before you make your decision, you should know how you plan to use your computer. If you are planning to use it for audio editing and mixing, then a USB audio interface will do. A Firewire audio interface is also quite popular. However, before you get too excited and buy an audio interface, you need to consider one important fact: all interfaces have their own advantages and disadvantages, so it is advisable that you read a number of articles and reviews first to know the pros and cons of the particular audio interface you plan to purchase.
An advantage of using a USB audio interface is that it can support high quality audio formats such as MP3 and WAV. However, the compatibility of the audio interface with different types of computer operating systems is not guaranteed. Another disadvantage is that most modern computers come with a built-in speaker port which is not accessible with external speakers. You may need to install special speakers to get the sound quality you want.
An audio interface’s ability to capture the sound through the motherboard is one of its many advantages. However, some people may find this limiting. If you need to use the audio interface to capture sound from a video game console or a DVD player, then the video card port on your computer should be used instead. On the other hand, if you use the audio interface to capture audio from an MP3 player with an analog audio input, then an RCA input on your computer should be used. The reason why RCA is recommended is because it provides better sound quality than any other connection.
So does audio interface have any effect on the sound quality? Yes, but only in a limited way. It helps to lower the distortion that occurs when you plug in and unplug devices. However, you will also notice that using a USB audio interface can increase the amount of background noise that is output to your computer. This means that you will have to adjust the volume levels of your audio devices more than if you had simply connected them to your computer’s speakers.