I had a 505 and had to upgrade to a 707 for recording with my sony mic. I have a 907 sony mic, It has a AA batt included for a little bit of boost, but it's not going to be enough to record nature sounds. You can only record really loud music on the 505 via the line in (which is both optical and analog 1/8") I might strongly sugest a new Hi-MD (with a mic and line input, of course). They start at 199 and are totally worth it. You can use old dscs, and use it as a USB storage device up to 1 GB with the new discs (300MB with the regular old discs.) I just ordered an open box one from minidisco.com to replace my old units. The greatest thing is that you don't have to plug the headphone line into your PC's audio card with all that hissing ant intereefierence. You can now uploaad music recorded from your mic directly to the PC using teh USB. I'm totally psyched to remaster all of my old recordings in total digital lovin'
