Best RCA interconnect up to ~$100?

+1 for Blue Jeans, it is a great place to start. 

I agree with others re Blue Jeans but would add it might help in determining when to move on, if at all, to having a set of cables with known different sound you can use. I recommend an inexpensive set of Mogami. They are different. When you can actually hear the difference it may be a good time to move on and it might as well point out the direction you should go. Take your time, don't get caught up in the hyperbole about cables. 

I’m already using Blue Jeans LC-1 now, upgraded from KabelDirect. Was just wondering what the next level would be. I’ve heard maybe try Worlds Best Cables Gotham or SignalCable Analog Two or SVS SoundPath.

I think you need to post your system to determine whether a cable upgrade is worth it. That money may be better spent elsewhere.