I have my Onkyo 595 hooked up with 16 gauge wire and decided to upgrade to 12 guage wire and banana plugs. I bought a pair of Radio Shack 278-306A banana plugs to test it out, and to my dismay, I can't plug them into the binding posts. I also have JBL NSP1 speakers with the same type of binding posts, and they don't fit either! Am I doing something wrong? Did I buy the wrong type of banana plug?