Two line-level outputs, one amplifier input
 

Hey guys,

I've got two line-level outputs (my MP3 player and my GPS system) that I
would like to be able to both output to the amplifier simultaneously (so
that the GPS speech will be audible over the music).

What's the best way to do this in a car environment? I'm guessing
simply plugging them both into the amp using a splitter is going to turn
the amp into an expensive paperweight?

Ideally I need some kind of mixer, I guess, so I can balance the volume
from each to my preference. Any recommendations - don't want to spend
silly money, but equally don't want to lose any sound quality.

Any ideas?

Cheers,

Alexis.