The RPG Optimizer is pretty much useless in all but a rectangular room. Don't waste your money.
The CARA program is capable of very good results, but as mentioned above, can be very demanding of your time and quantity / quality of data that it requires. Having said that, it can provide an extremely close "starting point" in terms of speaker placement.
If you want to take that a step further, you can use the data garnered from CARA and then optimize the installation by utilizing a digital room correction device to take temporary measurements. Using this approach, CARA gets you into the ballpark and fine tuning the placement using the digital room correction device gets you the best results possible. Once you've obtained the best results possible, you can then pull the digital correction device and listen to your system as you normally would.
Without CARA and using a digital room correction device by itself and taking measurements, you may end up trying a million different placements without obtaining as good of results as is ultimately possible. Without the digital room correction device and relying strictly on CARA, CARA will only tell you how your room / speakers should work theoretically, based on the data that you entered. Given that there are variables to individual building construction and the data that you entered may not be 100% accurate, the fine tuning using digital room correction tests makes up the difference between theory and reality and leaves little room for error.
The only problem with this approach? It can be VERY time consuming and the speakers may end up in a place where you don't want them or they aren't conducive to room lay-out. If you have a dedicated listening room, this isnt' really a problem. For those with their system in a room that is "community property", don't count on keeping the speakers in a convenient location. It just ain't gonna happen.
Other than that, it should be noted that CARA comes in both a metric and "Imperial" measurement platform. Make sure that you buy the one that you need or get ready to invest in a tape measure that has both meters and feet : ) Sean
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