Right off the bat, I'll bet you're wondering three things. First, what the heck is a vacuum-tube output buffer? Second, what does a tube-powered device have to do with getting world-class sound from a digital audio medium? Third, why would you ever want to buy one of these contraptions? The short answer to that all-important third question is that you'll experience the pleasurable musical equivalent of "shock and awe" when you hear the way $399 X-10^V3 transforms the sound quality of garden-variety CD players—lifting their level of play to a point where their sound competes with that of players with price tags running deep into four figures.