SAC by the way, stands for Software Audio Console

To take a quote from Bob Lentini (the developer of the software), "SAC is the acronym for Software Audio Console. This program runs in Microsoft Windows and turns your Windows PC into a powerful virtual Live Mixing Console".

"SAC opens new realms of live sound mixing capabilities with virtual mixing technology built around a core hand coded assembly language engine. The look and feel of a fully controllable Front Of House (FOH) console, coupled with 24 duplicate monitor mixing consoles with digital split points from 5 locations within the FOH Input Channels and 2 locations within the FOH Return Channels, creates a whole new way of mixing live sound while eliminating and replacing racks of physical equipment, snake cabling and splitters".

For more information about the software.
Software Audio Console

I have been using SAC on stage since the beginning of 2009 and just loving it. I run the sound from stage with a wireless laptop that has a usb keyboard plugged into it which resides on my piano.

The following is the host configuration:

• MOTHERBOARD - Gigabyte EP45T-UD3LR, Intel P45, Socket 775, DDR3, Gigabit LAN
• PROCESSOR - Intel E8400 Core 2 Duo, 3.0GHz, 6MB Cache, 1333MHz FSB, Socket 775
• MEMORY - 4 gig Patriot Dual Channel Viper, PC10600, DDR3, 1333MHz, Ultra Low Latency
• HARD DRIVE - OCZ Agility 2, Solid State Drive, 60GB, SATA II
• HARD DRIVE (backup) - 400GB SATA II
• VIDEO - ASUS EAH4350 Silent
• CASE - iStarUSA Aluminum 3U 17" Depth Rackmount Server Chassis
• MONITOR - Dell 19" Flat Panel
• AUDIO INTERFACE - MOTU PCI-424 with 24/IO Breakout Box
• MIC PRE's - PreSonus DigiMax D8, Nady PRA-8
• NETWORK - Belkin N1 Wireless Router

Pictured on the right is the live rig I use.