Great to hear that you got your video issue resolved. As for your sound issues I don't know if I can be much help there as there could be many reasons for the sound being almost silent.
It could either be some audio settings that are wrong on your PS3 or it could be the way you have connected your ps3.
What you can do is to try to change the audio settings and see if that will help. You can read more about that here: PS3 | Audio Output Settings
Or if you are connected through your XBox you could try to connect the cable directly to the TV and see if that helps. Thats really the best advise I can give, sorry.