Can You Plug IEMs Into an Audio Interface?

The short answer

For the MOTU M2, the manufacturer identifies a dedicated headphone connection. Use that documented connection when monitoring from the M2.

For a wireless Shure PSM300 P3T system, the listening connection is on the P3R bodypack receiver: Shure identifies its headphone output for earphones or headphones. That is a different endpoint from the interface’s output.

MOTU M2: use the headphone connection

The M2 Quick Reference identifies a dedicated headphone port and a separate headphone volume control. If you’re monitoring from the interface itself, use that headphone connection—not the rear quarter-inch outputs. The separate control matters in monitor world: the headphone level and the rear monitor-output level are not the same control.

The M2 Quick Reference identifies a dedicated headphone connection. Use that documented port for headphones rather than assuming another output is equivalent.

Why the rear outputs are a different job

MOTU describes the M2’s rear quarter-inch outputs as balanced, DC-coupled outputs for studio speakers, a PA, or another audio destination. It identifies them separately from the headphone connection. That is enough to make the routing decision: use the documented headphone port for headphones, and don’t plan around the rear outputs as though they were the M2’s headphone jack.

This is not a claim that the rear outputs can never produce sound into earphones. The manufacturer information here does not establish that they are a suitable or compatible headphone connection. The failure mode is assuming that a connector’s appearance settles the question. It doesn’t.

Shure PSM300: the P3R is the listening endpoint

In the PSM300 system, separate mixer outputs connect to the P3T transmitter inputs, and the mixes are sent wirelessly to bodypacks. The P3T is the transmitter side of that path; the P3R bodypack has a headphone output for earphones or headphones. Shure also identifies a P3R volume control that adjusts master headphone volume.

Keep those roles distinct when you’re tracing a signal. The interface headphone port is a wired listening connection on the M2. The P3R headphone output is on the wireless receiver. If the show-critical goal is to listen from the PSM300 bodypack, connect the earphones at the P3R output rather than trying to treat the P3T or the M2’s rear outputs as that bodypack connection.

A practical routing check

1. Monitoring directly from an M2: identify the dedicated headphone connection and use it for headphones. The M2 has a separate headphone volume control; the MONITOR-output volume control is a different control.
2. Monitoring through PSM300: trace the mix to the P3T transmitter, then to the P3R bodypack. Connect the earphones or headphones at the P3R headphone output and use its volume control.

Rule 1: Don’t substitute the M2’s rear speaker/PA outputs for its documented headphone connection just because the plugs seem to match. The routing is simple; the unsupported assumption is what creates the avoidable problem.

Who should choose something else

If you need a manufacturer-confirmed answer for a particular IEM model, or your earphones’ connection does not match the documented headphone port, don’t treat this guide as a compatibility sign-off. Check the exact product documentation or choose a monitoring path whose manufacturer explicitly documents your intended connection. That is the honest boundary of the available model-specific information.

Featured gear in this article

• MOTU M2 — audited specs, tracked street price, and rack fit in the planner.
• Shure P3T — audited specs, tracked street price, and rack fit in the planner.

Sources

• PSM300 / P3T / P3R manufacturer documentation (2.5 (2024-H)) — verified at review time (2026-10-16).
• M2 manufacturer documentation (2.035) — verified at review time (2026-10-16).