Ok I just discovered the REW and have downloaded the software to my windows XP computer. I have an internal SB Audigy 4 sound card. I have a line in jack separate from the microphone in so I will be using that but there are 3 line out jacks. Does it matter which one I use? Also do I need to hook up the optional soundcard calibration loopback? Also it mentions you can use a microphone but it appears the software is set up for the radio shack SPL meters. I would like to use the most accurate way. I do have the RS 33-2055 digital model and also two microphones one came with my Velodyne SMS-1 which seem pretty substantial and another that came with my Marantz av8003 ssp. This is so exciting! I love the SMS-1 software and didn't know there was something similar for the full audio range. I want to run my Audyssey and see if it actually can achieve a flat response. If not I should be able to manually adjust the EQ with the REW no? I'm already anticipating limitations due to my SSP's limited Equalizing points. However shouldn't I be able to use REW to apply acoustic treatments and speaker placement adjustments?