Upgrading to the Surround Signal Generator opens up the world of 5.1 Dolby Digital and 6.1 DTS-ES in AudioTools. Once unlocked, surround test signals will be available both as a standalone surround signal generator module, and as surround test signals available throughout many other AudioTools modules, such as FFT and Smaart. This module requires iAudioInterface2, iOS 5.0 or later, and internet connectivity to initially download the signal files. Starting with AudioTools 5.4, Surround Generator also works with the Apple HDMI AV Adapter, with later model iOS devices, like iPad mini and iPad 4. Note that the DTS 6.1 signals are not supported by the Apple HDMI adapter.