Ok, somebody please talk me out of buying an external USB DAC for my second system...

I have a media server that I built (Linux, MythTV, etc.) that is connected to an Outlaw 990 via USB and it sounds great! That is my main system.

My second system only has a CD player as input but CDs are quickly becoming dinosaurs around my house and I am going to connect another media server to this system.

Now for my dilemma...

With the B Stock 990s going so cheap, am I crazy if I buy an external USB DAC instead? I could just buy a 990 and use it as a waaaaay overkill DAC unit on my second system. Couldn't I?