Over the years Katia used several different gears to sing in SL or Live around town. Here's her current set up:

Gear

Our Music Space
Our Music Space

Where my Hubby and I make music. His mess to the left, and mine to the right :)

Alesis Mixer MultiMix 8 USB 2.0
Alesis Mixer MultiMix 8 USB 2.0

Alesis 8 channel mixer - simple and efficient.

Duet by Apogee
Duet by Apogee

Not sure I like this, but it is connected and I use it at the moment.

Audio Technica Headphones
Audio Technica Headphones

My favorite!

Samson Mixer/Amp
Samson Mixer/Amp

This is an extra step. I have it connected, but you can go straight to the mixer.

Set
Set

This is pretty much all you need ( not necessarily in this quantity) One Mac, a Mixer, a Mic and a MP3 Player.

PROfx8 Mixer
PROfx8 Mixer

This is the one I am currently using, works well.

Audio Technica ATM 4050
Audio Technica ATM 4050

I have and had many Mic's but along with the Seinheiser EW100 this one is my favorite of all times.

Microphones
Microphones

My two favorites. The Audio Technica ATM 4050 and the wireless Seinheiser EW 100