Digital audio interface and mixers with a USB output are used to connect microphones, instruments, and other output devices to the input of your recording devices through a digital connection.

Just as with any other gear, there are many too many choices available and the cost can easily get out of control, without any guarantee that you're getting the 'best bang for your buck'.

First, let's clear up the difference between the basic difference between a mixer and an audio interface.

An audio Interface works as the translator between your microphone or instrument (analog) and your computer, tablet, or phone (digital) Although an audio interface can combine multiple microphones (or instrument sources) together, it generally offers only rudimentary control over them, and the price for quality goes up quickly.

A Mixer, also combines the signals from multiple microphones or other input devices together. The important difference is that in a mixer, you have much more control over the individual audio signals, add effects such as Equalization and other signal shaping tools. Now that many mixers also can act as the analog to digital translator between your audio sources and your computer, tablet, or phone, you tend to get much more bang for your buck.

An (old school) analog mixer does all of it's signal adjustment and processing in the analog domain. This tends to make them bulkier and heavier then a Digital mixer. They often offer less flexibility then an equivalent hybrid mixer and the connections from them to your recording device are generally less resistant to induced noise.

A hybrid analog mixer, offers one important difference. It has a built in analog to digital converter that outputs a digital signal, directly to your computer, tablet, or phone. Often some of the signal shaping can be done in the digital domain and their output connections will be highly resistant to induced noise. These start to offer more 'bang for your buck' then a straight analog mixer.

A Digital mixer converts your analog microphone and other input audio to a digital format right from the start. A digital mixer does all of it's processing in the digital domain, and then outputs both digital and analog audio signals for various purposes. most can connect directly to your computer, tablet, or phone and other recording devices. Some offer wireless control by a laptop computer, tablet, or phone.

A caveat is that a really cheap piece of gear will not cut it. They have noisy circuitry, poor analog to digital converters (for the digital ones) and generally have unbalanced input and or outputs that can prove to be a problem. You can learn more about the problems with cheap gear by reading on line reviews, or just stick with quality.

My own personal bias is to go with either a hybrid mixer, or even better, with a completely digital mixer, and bypass the audio interface route (for all but the simplest implementations).

Here's an important questions that can help you decide on the best purchase.

How many microphones and other inputs do you need to be able to combine at one time. If you're using this for personal recording use then you'll only need a few microphone inputs and a few inputs for other devices, like an electric piano, or a guitar or bass amp, or a player for backing tracks. If you're going to play with a group (now or in the foreseeable future), then you'll need enough inputs to accommodate all of the players.

You can certainly learn more about this topic on your own (YouTube), but let's dive into some suggestions in the next few FAQs. I'm focusing on Behringer products here, because I've been using them for many years and feel that they manufacture a robust product that offers superb audio and build quality at affordable prices. Behringer also offers factory refurbished equipment at: https://www.ebay.com/str/Music-Tribe-Factory-Store at prices sometimes well below retail.

CAVEAT: when mixer manufacturers talk about 'inputs' they are talking about the total number of inputs available, not the number of microphone inputs available.

GOING FURTHER

SMALL ANALOG / HYBRID MIXERS WITH DIGITAL USB OUTPUT

DIGITAL MIXERS CONTROLLED BY TABLET/PHONE/COMPUTER

BUT MY MIXER DOESN'T HAVE A USB OUTPUT