Any source to acquire high quality L-shape RCA?

You might want to consider a T-shaped splitter. Monster makes one for sale at Audio Advisor. Jerry Raskins Needle Doctor has one, too. The top crossbar of the T has a male at one end and a female at the other. The vertical leg of the T is a female. You would plug your interconnect into the vertical leg female socket and plug the male into your amp. You would be wasting a fraction of an inch of behind-the-amp space to the unused female arm, which would stick out the back. I know this is not exactly what you want, but it'll do the trick inexpensively if the exactly correct solution can't be found.

When you think about it the Phoenix or even the Radio Shack gold L's are higher quality than the rca inputs on the back of most high end pieces. i wouldn't over think this just to spend more money.