Many interfaces offer two 'versatile' inputs that can accept mic, instrument and line signals, and these are also suitable for more ambitious multitrack work, as long as you're happy to overdub one track at a time.
If you're recording your own live performances, you're unlikely to need more than one mic input for vocals and one instrument/line-level input for guitar/bass/keyboard, or two if you want to record your sources in stereo.
There are plenty of classic budget interfaces with two basic analogue inputs and outputs, including the Echo AudioFire2, Emu 0404, ESI Pro and M-Audio Audiophile 192.
So what inputs will you need? Well, if you're working with pre-recorded samples, loops and software synths, you may not personally record any signals at all, in which case the most basic stereo line-level input will almost be more than you need (although those two inputs are still likely to come in very handy at times, even if only to transfer other analogue-based music into your computer). However, if you're a guitarist, don't agonise over an otherwise perfect audio interface if it simply lacks an instrument input: you can buy a DI (Direct Injection) box that will let you plug a guitar into a mic input, or use one of the various 'Pod'-type preamps with line-level output for more control over your tone and effects (we'll be talking more about such options in the 'Useful Extras' section). Compared with mics, magnetic pickups also require a higher input impedance to avoid high-frequency loss guitars with passive pickups like to 'see' at least 100kΩ to avoid high-frequency loss, and preferably 1MΩ. The output from such pickups often falls between mic and line levels, and will overload mic inputs unless you're able to turn their gain down by a considerable amount. If you don't want to be faffing about buying extra preamps, look for audio interfaces that feature 'versatile' inputs that cater for microphone, instrument and line-level sources, such as Focusrite's Saffire, shown here.The third main type of audio interface input is for an 'instrument', most often the electric or bass guitar, but also the piezo pickups used on acoustic guitars and other acoustic instruments.
Those who already have an analogue mixing desk with input channels offering mic preamps and direct outs can patch these into the line-level inputs of an audio interface, while those with larger budgets can investigate more sophisticated stand-alone preamps that offer particularly clean or desirably 'coloured' audio. If you want to record with one or more mics and are starting from scratch, the most cost-effective option is to choose an interface with suitable mic preamps built-in. Microphones output a much lower-level signal, and therefore require an additional preamp to bring their signal up to line level, before it gets converted to digital form to enter your computer capacitor mics require a preamp that can supply 'phantom power', and these days, nearly all do so. The simplest inputs are 'line-level', and are suitable for connecting other electronic equipment such as mixing desks, CD/DVD players, synthesizers and preamplifiers. This is the most important question of all, since it determines how many simultaneous inputs, and of which types, you'll need. Follow this SOS step-by-step guide to make a more informed buying decision.
To successfully choose the perfect audio interface for your own particular requirements isn't difficult if you follow some basic steps to narrow down the options. After all, the best audio interface for a musician creating electronica may be totally different from one used to record a live band, while if you only require stereo inputs and outputs, within a given budget you'll generally get better audio quality than spending the same amount of money on an interface with eight or more channels. We're regularly asked on the SOS Forums 'which is the best audio interface?', but even if we know the available budget that question is impossible to answer without knowing what the person asking it wants to achieve. Whether you're a newbie or a seasoned pro, there's now a bewildering choice of audio interfaces available, at prices ranging from pocket money to arranged loan. You can narrow down the choices significantly with the help of our essential guide.Īt its simplest, an audio interface lets you record external sounds such as vocals and instruments into your computer, converting them from analogue to the required digital format en route, and performs the opposite function on the return journey from computer to amp/loudspeakers. The vast majority of computer-based musicians will need an audio interface, but with so many on the market, it can feel like an impossible task to decide which to buy.