As a budding game master, I find the use of music and sound effects to be something that really enhances the experience. I currently use my phone and a portable speaker (phone speakers don't have enough power).
As for actual audio, I use assorted sci-fi music I put into a youtube playlist for combat and ambient music, and I use the sound effects from the fallout games as tones on my phone, using it as an impromptu sound board.
What does everyone else use? I hear syrinscape is popular.
Syrinscape is amazing. Sadly, it's not supported on my Amazon Fire HD tablet, and none of my friends are interested enough to install it on their devices to even try it out. :(
Bit of a necro, but I'm really thinking about syrinscape. Sadly my iphone 4s can't get the app because it's too old. Does the paid version of syrinscape let you make custom soundboards with files from your computer? That is going to be a big selling point to me since I find the stock sounds to be a bit underwhelming.