amp/pre amp utilizing two integrateds

So before I try this connection, I'd like to get a little input on the do's and don'ts. I am considering using a Rega Elex R as a pre amp for my Mac MA6450. As simple as the connections look and sound, I obviously don't want to ruin anything, and I have not attempted this before.
Pre amp output from Rega, to Power Amp in , on the Mac. and then there's the INT/EXT switch on the mac?
What mishaps could arise from this connection? TIA