These days there has never been more ways and choices of getting your sound into and out of your PC or Mac. Lets take a look at of some of the features audio interfaces have to offer so that you’ll be prepared to find the interface that’s right for you and your budget!

Inputs And Outputs –

This is probably the first thing you’ll need to consider when choosing your audio interface and it will also have an impact on the other factors involved with choosing one as well. Ask yourself, what do you need to get into your computer? Are you recording all of your band? A couple of groove boxes and turntables? The main difference here is that if you plan on using your computer like a multi-track recorder, that is recording each instrument into it’s own track in your DAW, you’re going to need an interface that gives you an input for each instrument. There are many choices as far as interfaces go and what sorts of features they offer, so it’s up to you to know your own needs in this regard. However on the other side of the coin, you can use an external mixer and record into an interface that only has one set of inputs as well. This is generally cheaper that a dedicated mixer interface, but the down side is if you want to muti-track, you’ll need to record one instrument at a time. In contrast, if you plan on using VSTis mainly with your DAW, you could very easily get away with a basic audio interface.

All interfaces have at least one set of outputs, either in the form of RCA or 1/4 inch jacks, to connect to a set of speakers. You may want to consider an interface with more than one set of outputs if you’re planning on connecting back into a mixer or want multiple sets of speakers to either enhance or compare the sound. The speaker outputs are line level, which means if you want to hear the audio, you’ll need to power it with an amplifier, a headphone amp or a set of monitors with a built in amp. A good thing to look for in this case is a headphone output on the interface your considering. Most of them have one, but it’s a good thing to take notice of. Also, if you’re just starting out, a good set of headphones is allot cheaper than a set of monitors.

ASIO & Duplexing –

These are pretty standard on audio interfaces, however if you are considering the more budget friendly interfaces, these are things you’ll want to keep your eye on.

ASIO is a high performance, low latency audio driver and it eliminates the noticeable lag in your computer’s audio and overall performance if you are not running it. The effects of this are particularly noticeable when running VSTis and when playing back audio from your DAW (Digital Audio Workstation). Typically ASIO is installed as a driver for your audio interface and then selected as an audio device within your DAW program. For those of you still running factory sound cards, you can download a free universal ASIO driver called ASIO4all.

Duplexing is the ability of your audio interface to play audio as well as record it at the same time. This is needed if you want to, for instance, record your guitar while playing to a rhythm track from the computer or provide voice over dialogues for video editing.

Again, while these are pretty standard features on recording quality sound cards, it’s a good idea to familiarize yourself with selecting and activating these features through your DAW and audio interface’s driver and software (or even sometimes hardware.) Simply reading the included manuals or online help will save you headaches in the long run when want to use these features.

DACs & ADCs –

For the sound to get in and out of your computer, you need something to convert the sound from one form to another. Inside of the PC is what we call the digital domain (or ITB for In The Box) and you need to convert it into analog, which is the form your speakers need to able to reproduce the sound. So naturally, a DAC is a Digital to Analog Converter (outgoing sound) and a ADC is an Analog Digital Converter (incoming sound). An ADC would correspond with a microphone input or line level input and by the same token a DAC would correspond to a speaker output.

Getting into the actual processes of how this actually happens is a bit beyond the scope of this article, but one thing I will say is that the quality of the DACs & ADCs determines the quality of the audio interface (they actually are the interfaces!) or any audio interface for that matter as they are found in almost anything that reproduces sound from a digital source in some way: DVD, CD & MP3 players, etc.

From here we could get into discussions about sample rates, frequency responses and other technical mumbo jumbo, but for now, lets stick to the basics. At this point, if you’re shopping for your first “prosumer” level audio interface it’s safe to say that anything you buy from a musical dealer is going to be head and shoulders in quality above any card you could get at a computer supply retailer. And shockingly enough in most cases recording quality interfaces are the same price or even cheaper than some of those famous high quality cards for gaming or movie watching.


SPDIF (Sony/Phillips Digital Interconnect Format) is a digital output that is offered on some audio interfaces. Rather than being converted into analog as it exits the interface, it stays in the the digital format with the intent that it will be connected to another piece of gear that has a SPDIF input; which could be anything from a minidisk recorder to monitors.

Is it something you need? If you’re just starting out and don’t intend to use higher end recording and mastering equipment, then no. But some monitors do have an SPDIF connection along with the 1/4 and RCA varieties and the schools of thought on that seem to be divided on if it’s really useful or not. The thinking is is that the output sound stays digital until it gets to the speaker, so it stays free of interference. Usually monitors are used in the same vicinity as the DAW and the cable run between the audio interface and the monitors is so short, it doesn’t make much difference anyway. So while the jury is out on this one, I can personally guarantee you’ll be fine with regular old analog outputs.


Some audio interfaces incorporate on board MIDI (Musical Instrument Digital Interface). MIDI is sort of a networking protocol for musical instruments such as synthesizers and drum machines that allows them to connect to each other as well your DAW for the purposes of transferring information. This would allow you to connect a keyboard such as a synthesizer to your DAW and have it play back a musical composition you’ve written within your DAW’s sequencer. MIDI is not audio, MIDI is only designed for carrying information such as note values. So even though your keyboard has a MIDI out jack, you’ll still need to hook up the audio outs to your audio interface’s audio in jacks.

Having on board MIDI is really a matter of personal preference, considering how many combinations of features there are to be found on audio interfaces. If you’re just starting out and perhaps are considering an all in one style interface, having on board MIDI as well as effects (which are covered in the next section) can really add some bang for the buck.

Effects –

On board effects are usually aimed at guitarists who mainly record into an audio programs like Sony Sound Forge or Audacity where they don’t have access to a full suite of effects. For the most part, you’ll have effects on your keyboards, in your DAW or as external units that will be more flexible to use. But there’s nothing saying you can’t use them to process incoming audio either. Again, this is mainly just a choice of personal preference.

Volume Controls –

This is sort of a random item here. Most audio interfaces don’t have on board volume controls for the audio. Instead, they rely on the volume controls on your mixer, synths, DAW and monitors to control the audio input and output. I personally feel it’s handy to have volume controls right on the interface, along with a headphone jack. Again, it’s not needed so much if you have monitors with a volume control, but it does help tame incoming audio that may be too hot. Just one of those things I enjoy, but your mileage may differ.

Which Format?

This mainly depends on which format PC or Mac you have; either laptop or desktop. There are three main types of connections to the DAW that audio interfaces use: Firewire or USB, PCMCIA or internal bus.

More than likely, you’ll end up with a USB or Firewire audio interface. Why? They have the most in terms of the ranges of prices and features they cover, so there’s quite probably one out there that’s right for you. And there’s really no drawbacks to using one either: there’s no latency to speak of and noise is virtually nonexistent. Not to mention they are easy to setup and connect to your computer, requiring only basic computer knowledge.

On the other hand, PCMCIA (sometimes called cardbus or PC Cards, which are also for laptops only) and internal bus (desktops only) audio interfaces tend to be more expensive and require more specialized computer knowledge to get up and running. Higher end DAWs such as Pro Tools also tend to require these interfaces as well.

Again, unless you’re in a high end situation requiring extra DSPs (Digital Signal Processor) or specialized hardware, you’ll be fine with any of the USB or Firewire interfaces. Just remember to pick the one with the features you need and give yourself some room to grow.

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