Yamaha wasn’t a major iPod speaker maker, but with the recently-released four-driver audio system PDX-30 ($200), it’s obviously ready to take an aggressive stab at the combined iPod and iPhone audio market, though with a few notable wrinkles. The company calls PDX-30 a “portable player dock,” but it’s not the dock that’s portable; rather, it’s a dock for portable iPhone and iPod devices, and runs strictly…
