What kind of input sources are supported?

What kind of input sources are supported?

So far I have chosen to design these as power amplifiers with a single line-level input and a volume control. For people looking for multiple inputs and switching between them, I usually recommend a preamplifier. Everyone has different source needs--some looking for a phono stage, others just line level, and so on. If you just need a few line level inputs and switching, then I would recommend a passive preamplifier as the simplest method. If you have low-level sources or use a turntable, then you would want a powered preamp.