It began with smartphones, first introduced a decade ago. Year by year, these devices, which are actually tiny computers, have gotten increasingly more powerful. Today’s smartphones can do it all — from handling sophisticated audio production to processing 4K video.

Single, high-quality USB and Lightning-connected microphones for smartphones have now been supplemented by a new category of product: sub-micro-sized audio mixers and interface controllers. Several factors have propelled this move to these pocket-sized devices.

Sub-miniature electronics with professional level circuitry ensure these tiny components sound great with portable devices, which include iPhones, iPads and Android phones. Mobile news reporting, podcasts, video and musicians have created a need for multiple mics and other audio inputs in the field. And the convenience of carrying a professional recording rig in a tiny bag is overwhelming.

One such mixer, introduced earlier this year, is Roland’s Go:Mixer, a tiny four-ounce audio mixer with eight input channels. The Go:Mixer is flexible enough for users to connect a microphone, line level and/or guitar, bass, keyboards or other high or instrument-level devices. The bus-powered device connects to iOS or Android devices via USB Micro-B and outputs a digital stereo audio feed. Hooked to an iPhone, it can even support videos. Price: $99.99.

Yamaha’s SC-02 SessionCake is another portable battery-powered audio mixer ($99.99) that features a mono XLR input for a dynamic microphone and two ¼-inch Hi-Z inputs for guitar, bass or keyboard. The built-in mixer allows users to monitor the source via headphones without needing an external power supply.

The supplied 3.5mm TRRS cable connects to a smartphone or tablet. Plug-in headphones to the 3.5mm headphone output. Front-mounted controls deliver control over level and panning adjustments. The mixer is powered by two AA batteries and weighs 8.9 ounces.

Shure MVi ($129.00) is another pocket-sized USB recording interface with five DSP recording modes and headphone monitoring. It works with standard Macs and PCs with a USB connection or with iOS devices using a cable with a Lightning connector. A Class A preamp includes phantom power for a condenser mic, and the DSP allows dial-in EQ and dynamics settings. The recording is 24-bit/48kHz.

For podcasting and voice-over work, where the user needs to record a single track at a time, the MVi offers a very high quality, portable option. Especially useful is a free Shure app on the iPhone that can program the MVi's DSP. Those settings can be taken into any other app, including third-party video apps or an iOS DAW.

On the more expensive side is DPA’s d:vice MMA-A Digital Audio Interface ($659.95), which captures 24-bit, 96kHz audio to a laptop or iOS device via USB. With this round, pocket-size 1.8 ounce digital audio interface — about two inches in diameter — users can achieve studio-quality two-channel interviews in mono, dual mono and stereo.

The free DPA d:vice app allows access to the MMA-A's deeper settings and takes full advantage of its capabilities. This flexible interface is compatible with all MicroDot-equipped DPA microphones and works with most third party apps. It includes micro USB-B to iOS (Lightning) and micro USB-B to PC/Mac (USB-A) cables.

Using the DPA app, the “Gain” slider can be adjusted to input levels. The “Filter” button activates a built-in high pass filter. The “Mon” button can be used with headphones to monitor what’s being recorded. The user can prevent third party apps from controlling the gain settings with the “Lock” button. And there’s a choice between mono, dual mono and stereo recording. All preferred settings can be set as recallable presets.

Just as with more traditional-sized audio mixers and computer interfaces, the smaller ones come in all shapes, sizes and prices. Each is targeted to a specific part of the audio market, though most can be used for any portable audio application on a smartphone.

Now that the gates are open, expect to see dozens of newer, more user specific models in the coming months. Each will be targeted for a particular application, ranging from news reporters, podcasters, broadcast voice-over artists to musicians who want to do a quick video on the fly.

What we couldn’t have dreamed of a decade ago, is now reality. The most difficult part is finding the creative uses to put this technology work to tell a unique and compelling story.