If you like the sounds your RP makes, you’re probably going to want to record with it. There are three ways to do that, and all of them work well.
1) If you like the sound of the RP through whatever amplifier you’re using with it, then you can just stick a mic in front of the amp speaker and hit RECORD on your recordng device–exactly as if you were recording an electric guitar from an amp. A Shure SM57 mic or equivalent, placed an inch or so from the speaker grille and facing straight into the center of the speaker cone, is a good place to start. We recorded our RP155 patch samples with a Zoom H4 right in front of the speaker grill, and it worked fine for us.
2) If you already have a decent audio interface for your computer, or good inputs on your recording device, you can run cables from the XLR outputs or 1/4 inch outputs on the RP directly into your audio interface or device inputs. Use LINE or INSTRUMENT level inputs for this purpose, NOT mic level inputs. Recording from the stereo outputs gives you the full flavor of effects like the rotary speaker, flangers, reverbs, and delays, which is very cool, but if recording inputs are in short supply, the RP sounds fine recorded in mono too. Remember also that if you use the XLR outputs, you MUST use both–the only mono output is the left 1/4″ out.
3) Since the RP is itself a 24-bit digital audio interface, you can connect the RP to your computer via USB for recording directly from the RP. We’ve done this ourselves on a couple of recent sessions, and the clients loved what they heard. (For a closer look at one of these sessions–the parts I recorded for episode 3, season 2 of the BBC series “Copper”–check out this post.) Any patch that’s active on the RP at the time of recording will process the input signal before it gets to the output. In this case, you MUST have previously downloaded the correct audio drivers for your specific RP device from Digitech.com and installed the drivers on your computer. Once that’s done, you will probably need to go into your recording software and tell the software to use the RP as your audio input and output device. See the instructions for your recording software to find out exactly how to do this; in most cases, your software will have a menu that shows you all the available input and output audio devices on your computer, and you just check off the ones related to the RP.
Any of these techniques can produce good results. Watch out for digital clipping (which displays visually as squared–off waveform tops in your audio recording software), and lower the level of the RP’s outputs or the recording device’s inputs if necessary to get a signal with a level that’s neither zero nor clipped.