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Everyone's going crazy for single-ended power amplifiers. What's the big deal? What is it about these relatively low-powered contraptions that could make everybody so nutso? And has Pass Labs' Nelson Pass completely lost his marbles, selling a 30Wpc amplifier for a price that can buy a high-quality 200Wpc amp? Isn't that 200W amp seven times as loud—and seven times as good—as a 30W amp?

One of the fundamental tenets of high-end audio is that a loudspeaker's bass output should be appropriate for the listening room's size. The smaller the room, the less bass the loudspeakers should produce. Any manufacturer of large loudspeakers who has set up such a system in a CES hotel room can attest to how difficult it is to avoid boominess in a tiny space.

Latest and largest in Krell's current range of power amplifiers, the 600Wpc, $12,500 Full Power Balanced 600 joins the 300Wpc FPB 300 ($9000) and the 200Wpc (originally 150Wpc) FPB 200 ($5900). All are single-box stereo chassis and are specified as "Full Power Balanced"—I think to distinguish the essence of these designs from ordinary stereo amplifiers operated in balanced-bridged mode, usually with impaired performance. The FPB 600's speaker output is balanced; ie, neither "positive" or negative" terminals are connected to ground or the amplifier chassis. (Note that no speaker switches or headphone adaptors, which often have joined channel grounds, may be used, as they will short the outputs.) The output terminals are electrically at 0V, but float above the chassis ground.

While I was working on my review of the K-1 preamplifier, I telephonically corralled Ayre's Research Director Charlie Hansen for a midwinter afternoon's gabfest. I started by asking Charlie how he became an audiophile.