I have a few questions about some rta-12b's that were given to me last week. the speakers work great love the sound but I am curious about hooking them up. I have a 200 watt onkio receiver that can be set at 6 ohm or 8 ohm. the polk speakers are 4 ohm and I also want to hook up some jbl bookshelf speakers that are 8 ohm. am I better off chaining them and using the 6 ohm setting. or hooking the polks up to a and the jbls up to b. would also like to hook up my outdoor speakers. so the chain method would have benefits leaving b open for them. I am also curious if this is where I might find a new cover for the top. previous owner is still looking for missing one.