Jim,
If you determine that you need to stick some method of lowering the output into the line out of your Sony, I have a pair of the Rothwell attenuators that I could sell. Not trying to poach your thread, but the Rothwells are a bit expensive when you have to order them for the UK (which I did). I'm not currently using them. They were purchased to help equalize the output of a CD player and a phone stage that had a large difference. They work as advertised. I believe mine are the -10 db version, but I could double check if you are interested.
If you determine that you need to stick some method of lowering the output into the line out of your Sony, I have a pair of the Rothwell attenuators that I could sell. Not trying to poach your thread, but the Rothwells are a bit expensive when you have to order them for the UK (which I did). I'm not currently using them. They were purchased to help equalize the output of a CD player and a phone stage that had a large difference. They work as advertised. I believe mine are the -10 db version, but I could double check if you are interested.