Sorry if this sounds slightly on the dumb side for this forum but if I connect my blu ray Sony BDP S390 to my amp using the rca yellow, red and white cables (will upgrade depending on answers!), will I get a comparable video signal to that which I currently have using the HDMI cable? I have heard the audio is improved but don't wish the picture qualty compromised.
No. Use HDMI. You can't get 1080 resolution with the yellow cable. And you can't get multi channel sound with the analog red and white cables.
The audio won't be improved, either. Most players will output exactly what is on the disc over your HDMI cable to your amp, so there's no improvement to be had.
The video quality will be severely compromised; that yellow connection didn't even hold it's own to S-video or component cables.
If you have a player old enough to have RCA outs, connect the red and white cables to your receiver so you can use it as a CD Player and listen to music while the TV is off. That's what I do. But you should still have it connected either to your AV receiver or TV with HDMI for high def viewing.
I dont know if thats possible. My Sony TV setup menu lets you choose one or the other but I will try.