So-called Class D or analog switching amps are continuing to invade the audiophile landscape. That Audio Research as one of the tubular (and linear) stalwarts of American HiFi had gone Tripath with a specific model years ago is well-known. That Cary Audio just announced a Class D amp that seems based on ICEpower from the specs is a newer development. Bel Canto Design of course started the phenomenon in HighEnd audio together with TacT. The firm from Minneapolis is now in its 4th wave of digital amps and the latest series dubbed e.One prefers ICE over Tripath. Lehman Audio from Germany just announced a 20wpc analog switching amp. AV123, for their new X-Series, will have a Class D amp. Kharma's new ultra-compact solid-state amp nearly screams Class D even though the descriptions surrounding it indicate something different again. NuForce is making big waves with their proprietary take on the subject. Channel Islands Audio received a very favorable Stereophile review for their Hypex-based monos. So did PS Audio for their Class D amp. Audio Magic makes a pair of ICEpower monos called the Stealth 250s. And so on.

No matter how you look at it, this breed is here to stay. It is no longer content in subwoofers or Japanese mass-market receivers. To date, such amps are still viewed as the challengers of the status quo. Accordingly, they find themselves compared against the best of traditional linear amplifiers - by Pass Labs, McCormack, Krell, Levinson and Classe. So far, I'm not aware of a strong consensus that the new breed is better than the old. Rather, most commentary I've seen is surprised by how close in performance the new gets to the old - for often considerable less money, less heat and less size. Can the day be far away when a particular design -- or the genre as a whole -- advances far enough to be considered "as good" or "better, period" than the old? Will traditional Class A at least in transistor designs eventually be rendered obsolete?

If Audio Research, Conrad Johnson and Cary Audio are the three most established American tube electronics lines (with BAT being younger), the fact that two out of the three now offer Class D amplifiers seems telling. Arguably the real test will be the appearance of one such amplifier from a traditional Class A amplifier maker to suggest perhaps not superiority but full equality. Will we see an analog switching amp from Krell or Bryston? Your guess is as good as mine. But it now does seem like a distinct possibility, doesn't it? It's also noteworthy that valve makers would embrace this genre as though to whisper "it's perhaps not the same but it's darn bloody close - with no headaches". And of course Jeff Rowland has long since embraced the Class D topology as equally worthy of impeccable implementation as traditional Class A. It seems the new force really is with us now for good.