Can I connect two sources to my speakers?

The A5+s have two inputs, so having two sources plugged into them is perfectly fine. There isn't any sort of auto switching mode built into the speakers so if you had both playing at the same time, both would be audible. The A2+s and HD3 also include a USB input; you should be able to use the USB input as well as the mini-stereo/RCA inputs to connect three sources to the A2+s.