Cable connections to an old receiver?

I'm setting up my first "real" stereo system and I'm wondering about the connection between my speaker cables and my receiver. I've got an old marantz that has the little boxes with holes in them and then a lever that you push down when you put the wire in the hole and then the spring pushes the lever back up to hold the wire in place (I'm sure this has a specific name but I have no idea what it is). When I ordered my cables, I described my situation to the cable maker and he suggested that for the best sound I should just use bare wires or he could sodder the ends (no spades or banana plugs). I chose to have him sodder the ends so that I wouldn't have the upkeep of bare wires. When I finally hooked up my speakers and cables last night, everything seemed to work fine, but the connections to the receiver seem less than totally stable and tight. I'm wondering if maybe I'm losing some sound due to a flimsy connection. Should I make a change? Is it fine how it is and it's just going to be a little loose? Suggestions?
Those are pin terminals, and they're really awful. I'd remove all of them and install a set of five-way binding posts.
Assuming there's good contact between the entire cable and the terminal (which presumably there is if the cable ends are soldered), you should be ok, soundwise. From your description, it doesn't sound like they are actually coming loose. But it wouldn't hurt to upgrade the terminals, either.

It's also possible that the soldering, by making the cable ends stiffer, is making it harder for the terminal to grasp the cable. Attach a piece of bare wire to a terminal, and see if the connection is firmer. If it is, snip the soldered ends off your cables and use bare wire.
Monster Cable has a gold plated braid cable termination that's flexable for those old spring terminals. I've used them on my old Pioneer SX-1250. Just add shrink tubing around the threaded barrel for added protection againg shorting as those spring terminals weren't design for large O.D. cables.
Does anybody else besides monster make those cabe terminations? I'm using a somewhat cheap but still nice DH labs cable and I'd hate to corrupt the sound with a lesser termination. Or maybe monster stuff isn't as bad as I've heard?