Are you using a USB or FireWire audio interface to record your demos? You could use a stereo DI box from your keyboard or mixer with the ground lifted.
Jonathan:
I am using a Sound Blaster Pci card in my PC. Do I need an audio interface?
Please explain to me how I can improve my recordings. I checked a tiny mixer with usb port:
http://www.alesis.com/multimix4usbIs the DI box you mention something like this (the price is in pesos don't panic):
http://www.famusic.com.ar/JR/PHONIC-DB2-Activa-Caja-Directa-0803151616101806.htmlThank you.