> Any signal quality loss will be pretty negligible really, so long as the splitter is of decent quality (which that one should be). If you have 2 things plugged in, you'll experience a drop in volume though, as the power of the output is being shared between two devices.

You can't use that splitter in reverse however (taking 2 inputs and combining them into 1 output) as that's not the way to sum line level signals, you need additional parts to do that so that the signals do not interfere with each other.

> It's generally OK to connect two inputs together (the input of your stereo and your house stereo). You could probably connect 5 or 10 inputs together before you have a problem. If you connect two headphones at the same time, you might hear a difference due to the lower impedance load, and you have to be very careful about connecting speakers together. But, high-impedance line-inputs are not a problem.

It's a BAD idea to connect two outputs together.... For example, you shouldn't use a Y-Adapter to connect your iPod and CD player to your stereo system at the same time. And, you …