Porthole will have you streaming in no time. Follow this guide to start.
Extract the .zip file (if Safari hasn't already done that for you) and move the file to the Applications folder.
Launched Porthole from Downloads? Porthole will ask you to move it automatically. Super nice!
Launch the app by double-clicking it in your Applications folder.
The first time you run Porthole, it'll launch the Setup. Follow these steps to install Soundflower and start streaming.
Select AirPlay Speakers
Use the icon in the menu bar to select which speaker(s) you wish to stream to.
Adjust the Volume per Speaker
Adjust the main AirPlay volume, you use the volume keys on your keyboard (F9, F10 & F11). The volume in the AirPlay device goes from 0 (silent) to 30 (loud).
If you go into Preferences → Volume, you can add adjustments per speaker.
By dragging the slider you can add to, or subtract from the main volume. This means that if the main volume if 10, the volume of SandroTV will be 25 and the volume of Danger Cove will be 5.
This is not a volume boost; if the main volume is 25 and you add 10, the volume will still max out at 30.
My advice is to set the main volume at about 75% with the volume keys and use the sliders to setup the rest. All settings are saved automatically.
Toggle Mac Speaker
You can enable and disable synced playback through the built-in speakers (or connected speakers) on your Mac.
Simply click the menu item and adjust the volume.
If the music starts off out of sync, simply disable and re-enable the computer speaker and it'll sync up.
Remember that the volume slider is connected to your Mac's output volume. If you stop streaming the same volume applies.
Menu bar not fast enough? Try the Hotkey Panel to switch speakers with a keyboard shortcut.
Activate the panel by pressing the hotkey combination (default: ^⌘P).
Press C to connect to all devices and D to play via your Mac's speakers.
Use the number keys (1, 2, 3 to 0) to quickly toggle the first 10 devices.
To close the panel, click outside the window or press Esc.
If you want to automate things, or control Porthole without going through the interface, scripting is the way to go!
Read the Scripting Tutorial to get started.
Make Porthole even more comfortable to use by setting up up the remote control.
Read more about how to adjust your AirPlay setup away from your Mac.