I just received my sound card that I purchased from ebay. I was starting to set it up for REW by downloading all of the drivers and apps. I cannot find the Surround mixer app. Is this necessary? I see in this thread http://www.hometheatershack.com/forums/spl-meters-mics-calibration-sound-cards/875-soundblaster-live-24-bit-usb-external-setup.html that changes are made in the mixer, so I assume it is. Can anyone help? Thanks.