A lot of the iDevices have some form of a dock and remote control to go along with them. If you really want the stereo sound, or a more varied sound, you are going to have to get a remote or just have to get up and physically make the change.
Well there is help for you. There is a free app called iKeyboardRemote. This is a Mac app and with this app, you can control the basic iPod function while you are sitting at your desktop. It is free, easy to use and uses the Bluetooth connection between your Mac and your iOS device. It is not hard to setup and again it is easy to operate.
After you have downloaded the app, you can follow the install directions which will take you through the process of connecting your computer and your iOS device. After the get on the same wavelength, the media keys on the keyboard will control the playback. With the media keys, you will be able to skip, play, pause and adjust the volume. Since it is Bluetooth and not WiFi, the range may not be very long, but it is still better than getting up and having to change it each time.
Again, it is free and you can download it from the Mac App Store. This app is what we could consider an application of convenience, but oh what a convenience it is. So go ahead and download this app and make your music listening experience much easier.