Warmline

Warmline for macOS

Support

Setup, permission, and output guidance for keeping Warmline between your Mac and the speakers you want to hear.

Before you start

Warmline requires macOS 14.2 or later because it uses Apple's system audio process taps. It runs from the menu bar rather than opening a normal Dock window.

  • Play audio in Music, Safari, Spotify, or another Mac app.
  • Open Warmline from its vinyl record menu bar icon.
  • Choose an output, then press Play in Warmline.

Restore system audio access

Warmline needs System Audio Recording access to hear the playback it processes. It does not use this permission to save or upload audio.

  1. Open the permission panel.

    In Warmline, choose Open Settings. Or quit Warmline, then open System Settings > Privacy & Security > Screen & System Audio Recording.

  2. Allow Warmline.

    Turn Warmline on. If it is already on but access still fails, turn it off, quit Warmline completely, turn it on again, and reopen the app.

  3. Trigger a fresh request if needed.

    If Warmline is not listed, reopen it and press Play to show the macOS prompt. You can also use the Add button in the permission panel to select Warmline from Applications.

After changing access, relaunch Warmline before trying Play again.

Use a local output

Warmline can route to built-in speakers, wired or Bluetooth headphones, and a connected USB audio device such as a DAC or interface.

Choose it in Warmline

  1. Connect or wake the output before opening the picker.
  2. Select it from Warmline's Output menu.
  3. Press Play in Warmline, then start audio on the Mac.

If it is missing

Reconnect the headphones or USB device and confirm it appears under System Settings > Sound > Output. Return to Warmline and use the refresh control, labeled Refresh Outputs for VoiceOver, then select it again.

Warmline remembers its own output choice. A macOS output change does not always replace the output already selected in Warmline.

Hand off to AirPlay or Sonos

Warmline uses the AirPlay destination that macOS exposes as the Mac's audio output. Sonos works when the speaker appears as an AirPlay destination.

  1. Choose the destination in macOS.

    Open Control Center in the menu bar, choose Sound, then select the AirPlay or Sonos speaker. You can also use System Settings > Sound > Output.

  2. Complete the handoff in Warmline.

    Return to Warmline and choose Use in Warmline when the handoff cue appears, or select the same destination from Warmline's Output menu. Then press Play.

Use the Mac output, not an app-only picker

Selecting AirPlay only inside Music or another media app does not expose that route to Warmline. Choose it from macOS Sound or Control Center first. Keep the Mac and speaker on the same network.

Match, Lite, and Studio

These controls change how Warmline processes audio, not where the audio goes.

Match
Match listens for about three seconds while audio is playing, compares processed sound with Bypass, and adjusts Gain so the two are closer in loudness. Keep Bypass off and Warmline running while it listens.
Lite
The streamlined, simpler DSP path. It has lower measured DSP-only work than Studio, but that does not promise meaningfully lower total app CPU. Both modes use the same shared Core Audio route, and that route dominates live utilization.
Studio
The default engine for new installs and the oversampled, higher-quality DSP path. Studio uses the fuller processing core for more refined parameter smoothing, filtering, and saturation.

Troubleshooting

No sound

Confirm audio is playing on the Mac, Warmline shows a selected output, and Play is active. Check the output volume, then try Bypass. If Bypass is also silent, refresh and reselect the output.

System Audio access needed

Open the permission panel, allow Warmline under Screen & System Audio Recording, and relaunch the app.

Output unavailable

Reconnect or wake the device, choose Refresh Outputs, and pick it again. For USB hardware, verify macOS can see it under Sound settings first.

AirPlay destination missing

Confirm both devices are on the same network. Select the speaker as the Mac output in Control Center, return to Warmline, and complete the handoff there.

Clicks or dropouts

Close high-load apps and test a local output. Compare Lite and Studio to isolate DSP behavior, but do not expect a mode switch alone to materially change total app CPU because both share the same Core Audio route. If local playback is clean, reconnect the AirPlay destination and check the network connection.

Processed sound is louder or quieter

Play a representative section, keep Bypass off, and choose Match. Warmline will listen briefly and update Gain.

That is expected: Warmline is a menu bar app. Look for the vinyl record icon near Control Center. If it is missing, quit Warmline in Activity Monitor and reopen it from Applications.

Still stuck?

Tell us what you hear.

Include your macOS version, selected output, and the message shown in Warmline. Please do not send recordings unless they are needed to explain the issue.

Email Warmline support