And the Explorer 2 is that kind of product: not quite a cup-of-coffee purchase, but $299 isn't too much to spend to escape a temporary funk. And beyond the low price, there was yet another good reason for pulling the trigger: Master Quality Authenticated (MQA), a new digital audio format from MQA Ltd., that promises big improvements in sound quality in small, streamable packages. The Explorer2 remains, as of this writing, the cheapest ticket into the world of MQA, and that world needed . . . well, exploring.