More information on this: I had to reboot the machine for something and when I went back into reaper, without making other changes, I was able to hear the playback in my headphones. Great, I thought, but not so fast... It'll work for a little while, but suddenly I can no longer hear the playback. Reboot, and again, it works, for a while.
I'm wondering if I have some kind of a driver issue, or some operating system issue. It's configured correctly, with x3's ASIO driver, and works after a reboot - I can even import a mp3 into a project, play it and record on another track, until it decides to go south...
I've made sure the drivers on my PC were updated (there were some updates - which I installed, though not sure if the ASIO drivers were on the list). I also discovered that the flash on the X3 needed updating, which I did. This all resulted in no change in behavior. I can hear the playback for a while and then it suddenly stops. Even when the playback stops, I can still here my live playing of the guitar through the headphones.
I'm at a loss, and its intermittent behavior is frustrating me. I'm at the point of where I'm just beginning to learn about recording my play. My long term view is to go the route of a audio interface and such, but given that the X3 is supposed to be able to do so, I'd rather not shell out the bucks on this just yet. Any help would be greatly appreciated.