I believe Craig's idea is the simplest way. It allows you to go to the first speaker, then run it to the second.

As an electrician, if I did that with 120VAC, I would be yelled at from my boss. Because he'll want me to run the 14/4 to the first (light) then a 14/2 to the second light. Understandable as 14/4 is expensive.

Now the question for you is. Would you run the 14/4 to both speakers? Or 14/4 to the first then 14/2 to the second? It comes down to cost. Cost of the wire and/or cost of the labor to run 14/4 then 14/2. You know, to climb the ladder then to climb down to grab the 14/2 and blah blah blah. For something that is done every once and a while, that "labor" of climbing up/down shall be tossed.

KOT