Rumor had it that if the MF2500 amplifier had gotten any better in development, Conrad-Johnson would have had to include it in their "Premier" series. However, C-J's intention was to hold to the lower price of their established MF series, and so they have. Rated at 240Wpc and retailing for $3495, the '2500 is the core model of Conrad-Johnson's current range of "MF" power amplifiers. Its companion MF2250 offers 120Wpc, while the MF5600 delivers 120Wx5 for multichannel home-theater applications.
Many tube aficionados hold that amplifiers built with the venerable 300B tube hold the aces when it comes to sonic purity and beauty of harmonic line. Cary Audio Design's Dennis Had succeeded in producing what many believe is the definitive moderately sized single-ended triode (SET) amplifier: the CAD 300SE. This monoblock, powered by classic 300B Western Electric or derivative tubes, could provide 8–10Wpc, requiring the adoption of relatively moderate volume settings and/or sensitive, easy-to-drive loudspeakers. Cary also produced a lower-priced "integrated" stereo chassis, the CAD 300SEI.
It's been five years since David Wilson's X-1/Grand SLAMM speaker system invaded our audio consciousness with its 500W power capacity and very high (95dB/W) sensitivity (footnote 1). Capable of an earsplitting 123dB at 1m, with a bandwidth to match, this was one speaker system that refused to be ignored. The X-1 has since evolved to $70,000/pair Mk.II form. It now provides some flexibility of tonal balance for different room acoustics, and is distinguished by greater subtlety in its differentiation of timbre. Beneath the X-1 in Wilson's range comes the WATT/Puppy ensemble, now in its 5.1 iteration (footnote 2). The WATT/Puppy has survived for over 10 years, and sets a benchmark for the Wilson line at its $17,270 system price.
While high-priced equipment can easily acquire stature on grounds of outright performance and physical appearance, we critics have more admiration for genuine achievement at lower price levels. One such product was the all-triode SP8 preamplifier from Audio Research, launched back in 1982 and priced at $1400. This classically tasteful preamplifier came equipped with a medium-sensitivity phono equalizer and the usual tape and line inputs.
Many pundits in our industry say that CD is under threat from Super Audio CD, DVD-Audio, and dual-layer CD/DVD technologies. Conflicting stories abound, and even though I'm supposed to be well-informed, I've found some of them hard to sort out! For example, Michael Fremer, concluding a fine review of the $7500 Bow Technologies ZZ-Eight integrated CD player in August, compared its notable 16-bit/44.1kHz achievement with a DVD-based disc originally mastered at 24/96kHz and replayed on an inexpensive DVD player. He found the Bow wanting in some respects. What is the world coming to?
In conversation with Cary founder Dennis Had at a recent audio convention breakfast, I learned that he had a long career in electronics, specializing in military/industrial high-power radio-frequency amplification and transmitters. However, his dream was always the re-creation of single-ended tube amplifiers, especially zero-feedback designs.
The search for signal transparency has led to much experiment and debate concerning losses in fidelity that can be traced to the preamplifier or—as it's more often and awkwardly called these days when the phono stage is omitted—the "line controller."
Although I retain a firm hold on the established audio world, and recognize and value all that it has achieved, I feel inexorably driven to make some space in my life for single-ended amplifiers—more especially, those that eschew negative feedback (footnote 1). A classic if costly example of the art is the Cary CAD-805C, which, to my ears, has earned the right to teach audiophiles what negative feedback really sounds like, and what damage it can do to the musical message when poorly handled. This shouldn't be taken as an out-of-hand dismissal of those many great pieces of electronics and amplification that use negative feedback—it is simply an acknowledgment, or even an assertion that negative feedback generates a sound of its own.
Over the years as a reviewer, I have tracked the swings of opinion and popularity of various audio ideas and technologies. Amid a sea of advanced designs that achieve powerful technical performance and laudable specifications, I'm reminded of a major blind listening test of 18 power amplifiers that I set up for the long-since-defunct UK magazine Hi-Fi for Pleasure back in 1975. We had "advanced technology" then: the transistor amplifier had matured and was well accepted by audiophiles. Prices of the review samples ranged from $300 to $3000 (equivalent to $1000-$10,000 in today's dollars). The auditioning sessions were graced by the presence of many industry leaders, among them the late Spencer Hughes of Spendor, Julian Vereker of Naim, Philip Swift then of Audiolab, Alan Harris then of retailer Audio T., Bob Stuart of Meridian, and John Wright of IMF (now TDL in the UK).
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.