That sounds like a low model number, implying fewer features.

Be sure it not only has a Zone 2 output (the exact name for what you are describing), but that it also has a power amp built into it that can be run at the same time as 5.1 is being run on the main zone.

I really have seen some Denon somewhere where you had to go out of 5.1 to use the second zone amps!

If it does not have built-in power amps for zone 2, but the price is right, you will need a separate power amp, but then the Denon has to have remote volume control of the zone 2 volume...the cheaper units do not always have that! And, if you need an external amp, is the price still right?

If it doesn't have internal power amps for zone 2, OR volume control for zone 2, you will need a second receiver or integrated amp so that you can control the volume of zone 2. Be sure that one is not a Denon, or both amps will respond to both volume controls. A bummer, that.