GUIDE · USB-C AUDIO
USB AUDIO
RECORDING
ON iPHONE.
An iPhone with USB-C makes a capable USB audio recorder. It takes audio from a class-compliant interface, synth, groovebox or sampler with no drivers at all. Here is what that means, what usually goes wrong, and how to get a clean take out of it.
LAST UPDATED 1 OCTOBER 2026
How it works
Class-compliant, explained
A class-compliant device follows the USB Audio Class standard, so the operating system’s own driver can talk to it. On a Mac or a PC that is a convenience. On an iPhone it is the whole story: iOS has no way to install a manufacturer’s driver, so a device that needs one will never appear.
Plenty of interfaces built for computers are class-compliant, and so are many grooveboxes, samplers and synths. The specification usually says so, or says it works with iPhone or iPad.
The phone end
An iPhone with USB-C takes a USB-C cable directly. The other end is whatever your device has — USB-C, USB-B or something else — as long as the cable carries data. iOS presents the device to REK. as an input. REK. reads audio from it, and nothing else.
REK. as a USB audio recorder
- 32-bit float by default, so there is no clipping ceiling on the way in.
- 44.1, 48 or 96 kHz.
- Stereo when the route offers it, with separate L and R ladders. A mono route shows a single M row.
- Uncompressed, always. Export as WAV, AIFF or AAC afterwards.
What you need, and six steps
Power, cables and levels
Power is the usual problem
A phone can only supply so much power over its port. A bus-powered interface that runs happily from a laptop may not run from a phone at all, or may drop out when the preamps work hard. If a device appears and disappears, or never appears, give it power of its own: its own supply, its own batteries, or a powered USB-C hub between it and the phone.
Not every cable carries data
Many USB-C cables are built for charging and carry power only. They look identical. If nothing appears, swap the cable before you suspect anything else.
Levels
The record path is 32-bit float, so a loud pass has no ceiling to clip against on the way into the phone. GAIN in REK. moves what you hear by ±12 dB and leaves the file alone, and the PK lamp latches so you know a peak happened. The one thing float cannot undo is clipping before the converter, in the interface’s preamp or the instrument’s own output. Set the source sensibly and let REK. handle the rest.
Hearing what you play
Monitoring is AUTO, ON or OFF. AUTO steps aside when you play a take back. If your interface has its own direct monitoring, set REK. to OFF and listen there.
When it does not work
My USB-C interface does not appear as an input
Check that it is class-compliant rather than driver-dependent, that the cable carries data and not only power, and that the interface has enough power of its own. Bus-powered units on a phone are the usual culprit, and a powered hub often settles it.
The meter shows one row instead of two
A single M row means the route is mono. Separate L and R ladders appear when the route offers stereo. If you expected stereo, check how the interface presents its inputs.
I think I recorded too hot
You almost certainly did not lose anything. The record path is 32-bit float, so there is no clipping ceiling on the way in. GAIN sets what you monitor, not what is written, and the PK lamp latches so you know a peak happened. Clipping in the interface’s own preamp, before the converter, is the one thing float cannot undo.
Which sample rate should I use?
REK. records at 44.1, 48 or 96 kHz. 48 kHz is the usual choice and what most gear runs at. 96 kHz doubles the file size, which matters on a phone during a long set.
Which formats can I export?
WAV, AIFF or AAC. WAV follows the take’s own depth, and normalize to −0.1 dBFS is off by default, so an ordinary export is a bit-exact copy. There is no MP3 and no stems.
Other guides
- A synth recorder for iPhone
- How to record your EP-133 on iPhone
- How to record Digitakt performances on iPhone
- Record your groovebox without a DAW
- Something else wrong? Support has the common situations and a human on the other end.
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