Inline CD Player - Does this exist?

[ablahblah]

I'm thinking of backup systems now and I was wondering, does anyone make basically an "inline" CD player? As in, a CD (or USB) player with an input and an output, and it passes through whatever's coming through on the input along with what it itself is playing. Sort of like a mixer and deck in itself, but not necessarily having any mixer controls. Does this exist, or is this kind of a unicorn product?

The application that I'm thinking of if this exists is to basically rig your existing controller setup to this, and have a CD/USB always on cue ready to go if your laptop and/or sound card dies. I know a good amount of people just patch their backup directly into the house mixer if they're using a controller, but I want to avoid bringing around an extra mixer for standalone scenarios.

[astromech]

If you're that worried about this issue, you'd be better off buying a modular setup with a mixer and transport MIDI controllers like a Xone:23C or even analogue. Or a controller that has capability to have a normal AUX in like the S5 so you can jack your phone into it. I don't think what you're asking for exists unless you bring a digital recorder with LINE IN and LINE OUT on with a few tunes on the SD card.