Space in my car was also tight so I ended up getting a 4 channel RCA like this one. In the picture on that site, it only shows the 4 cables coming together into 2. Those 2 also then come together into 1 single cable that is probably about the same size as an 8ag power wire. This is much smaller than buying 2 sets of RCA's and is easy to run. Those cables are shielded and I have had no problems with them ever since I installed them about 3 years ago.