As you know DGA, I use a power mixer pre-amp (a Eurorack) with phantom power going out to the left channel of a 2-channel Focusrite USB Audio interface. That Focusrite USB cable then goes to the computer. (Thus I keep the phantom power on the Focurite off and just use it as an in, two channel.) That is, the path is instrument to preamp, out to Focusrite, into computer.

I do that so I can get more "juice" without overloading the gain on the Focusrite, I also have control over the EQing using the mixer on the preamp before the sound hits the Focusrite, which gives you a LOT more control. The Behringer Eurorack is famous for being very inexpensive with almost no noise. I also use a booster on the mic before it even goes to the preamp and I still get no detectable noise in Real Band when I solo the vocal. Clean as a whistle. (I keep the gain the Focusrite channel around 9:30 and the level on the preamp at about 10:30, same for gain on the preamp. Those with softer voices will want higher settings.)

Also, if I want, I can have a vocal going in to channel 1 on the Focusrite coming out of the preamp, and the acoustic guitar going in to the right channel of the Focurite clean-- if I want an unadorned acoustic sound and I want to capture myself playing and singing at the same time on two separated channels.

You have to make sure to go into audio preferences in Real Band and set audio record L+R though. Most of the time, I just have it set to left.

It works really well for me and I hear it is a very common one man band home studio set up, though I thought I had "invented it."

It may not be for everyone, but doing this gives me exactly the sounds and "beef" I want out of tracks. (For electric guitar, I mic the amp, which is routed through the preamp.)

I also exclusively record audio into RealBand. It is my DAW of choice for recording audio, although I have Sonar, which I mix in.

Sonar is great for mixing, but I find it really glitchy with audio recording. Real Band never lets me down. It is my work horse.