AirPort Express 2nd Gen drop outs

I recently purchased an Airport Express 2nd Gen so I can stream music from my iPhone 5 through our newly-purchased audio receiver. Our router is located in a first-floor bedroom, and the AE is located in our living room, which is next to the bedroom. There is a wall between the two rooms. The AE and router are about 15 feet apart with a wall between them. The two devices are connected with an ethernet cable,

I am experiencing dropouts when I bring my iphone into our kitchen, which is about 25 feet from the living room (which is where the AE is located). If I move the iPhone into the dining room (about 10 feet closer to the AE), the dropouts stop.

I haven't tried moving the router closer to the AE as of yet, but I wanted to check with this community to find out if there's something else I should be looking into before doing this.

By the way, my router is is an actiontec MI424WR.