The simplest answer to your question is to get one of the One-For-All remotes. I would also get one that is equiped with JP-1(six pin plug in the battery compartment)like the Radio Shack 15-2104 or the URC-8811.
Then you can buy or make a JP-1 to Parallel interface cable. More information at
www.hifi-remote.com. That will allow you to program your OFA remote and then learn the commands to another remote. Either remote above including shipping are $35 to $40 and you can buy a cable for $20.
For most Sony TV commands you don't need the cable you can program in a three digit code known as an Advanced Code or EFC to just about any key (instructions also at hifi-remote) and that will allow you to send out any of the 128 possible commands for two main Sony TV device codes.
If the speakers and aspect controls are all that you are looking to do, I can't promise that your TV set even has them. I think some models will respond to some discrete aspect commands but I am not sure if a Speaker Off code exists.
-Jon
