Mic and line signals can be connected to the 2 XLR/TRS combo inputs on the front. Their levels can be adjusted with the dedicated knobs.

During the recording of a meeting, for example, while recording the line outputs of the meeting system equipment, you can simultaneously record two channels of mic input separately as a backup. In a music classroom, studio or similar situation, you can easily set up a system for multitrack recording and other uses using the line inputs for instruments with line output and the mic inputs for acoustic instruments.

The dual recording function allows a file to be recorded simultaneously at a lower level in addition to the main recording. If the main recording should become distorted due to sudden loud noises, you can use the backup file recorded at a lower level.
* When the dual recording function is enabled, only two inputs can be used to record.

In addition to the included AC adapter, the unit can also be powered by 4 AA batteries. If the AC power is interrupted for any reason, the unit will automatically switch to the AA batteries and continue operating without affecting recording or playback.

This unit uses SD cards, which are very common and easy to obtain, as recording media. Data files recorded with the SD-20M can easily be managed or copied using the SD cards themselves and a computer, for example.

SDXC cards with capacities up to 128 GB are supported. You can continuously record even long meetings and rehearsals, for example, with peace of mind.

Linear PCM recording is supported with resolutions up to 24-bit/96kHz. Since recording with high resolution is possible, you can capture music concerts and other important events with high levels of audio quality.

You can keep the sizes of files created smaller by selecting an MP3 format. By using an MP3 format to record meetings, discussions and other long events, you can record for much longer amounts of time on the same card compared to when using a WAV format.

The Variable Speed Audition (VSA) function allows you to change the speed at 50–150% normal speed (in 10% increments) during playback with this unit. Since the playback speed can be changed without affecting the pitch, this function is useful for language practice and meeting transcription.

The 2 XLR/TRS combo inputs on the front support balanced +4dBu line level input from mixers and other devices. They also support condenser Mics that require +48V phantom power supply. These features enable a wide range of setups. The locking mechanism also prevents the unintended disconnection of cables.

The RCA unbalanced inputs on the back support –10dBV line level input from mixers and other devices. Together with the XLR/TRS combo jacks, they enable connection of a variety of devices.

The automatic recording function starts recording when the input level is detected. For example, you can use this function to record a radio program. By setting a timer for a radio tuner and putting the SD-20M in standby, the SD-20M will start recording when the tuner turns on at the set time.