I recorded a test here with just one condenser capturing vocals and guitar at the same time to show how it sounds: http://dl.dropbox.com/u/17053397/sexual healing ruido).mp3 When I plug a condenser mic and turn the interface´s phantom power on, it works fine for about 3 seconds, then the input signal becomes very weak and a MASSIVE hiss emmerges. When I turn a second condenser mic, the hiss continues at the same massive level but the input signal of both mics decreases even more. Dynamic mics work fine. I´ve tried, with the same results: -Different USB ports -Different USB cables -External powered USB HUB -Notebook running on battery -Different computers An external phantom power supply to the mics should solve the issue, right? Probably a dumb question, but as I don´t know shit about electronics I figured I'd ask this here before ordering one.