Pass through to speakers?

[djBIGMac]

I've recently bought an MBP, the first Mac we've had in our house in nearly 20 years.
I do a lot of work with audio, I bought it to use for DJing but I'm struggleing with something that should be really easy.

On the line-in, how can I get it to pass the input straight to the output again?

Thanks in anticipation,
Ross

 

[Benjamindaines]

Down load Line In from here, launch it and click Pass Thru.