Balanced Audio Technology Rex II Preamplifier and Rex II Monoblock Power Amplifiers

Equipment report
Solid-state power amplifiers,
Solid-state preamplifiers
Balanced Audio Rex II,
Balanced Audio Rex II Monoblock
Balanced Audio Technology Rex II Preamplifier and Rex II Monoblock Power Amplifiers

About a decade ago at the Hilton Hotel in Manhattan, Balanced Audio Technology demonstrated its electronics in a magnificent surround-sound configuration with Avantgarde Trio loudspeakers and Bass Horns subwoofers that were parked in each corner of the capacious room. A line formed outside to wait to hear it. One of the demo cuts featured the Catalan tenor Jose Carreras performing with a choir. You could almost pick out each voice in the chorus. Carreras’ voice sounded utterly ethereal. It was one of those audio experiences that you tuck away in your mental sonic album and return to with a sense of nostalgia. [The same system at a San Francisco show elicited a standing ovation with wild applause at the conclusion of Pink Floyd’s The Wall—the only instance of such a reaction to a show demo in memory. —RH]

Ever since that event I’ve followed the progress of BAT, as it is known, with more than casual interest. A few years ago I visited the factory in Delaware where the equipment is built, and became acquainted with the very intriguing and variegated trio—Victor Khomenko, Steve Bednarski, and Geoff Poor—that runs the company. All three are passionate music lovers and Khomenko’s design knowledge is not be trifled with. The guy, to put it bluntly, is brilliantly innovative. Consistent with Russian engineering, which makes the most out of basic parts (think AK-47), BAT equipment appears quite impregnable when it comes to reliability.

Since I saw the factory, however, BAT has undergone a change in ownership. The original team remains intact, but the company itself was purchased by Music Direct owner Jim Davis in 2013, who has provided it with vital financial backing.

When Khomenko, Bednarski, and Poor visited me to deliver the company’s new 160-watt Rex II monoblock amplifiers and preamplifier, I was thus curious to listen to the equipment for several reasons. For one thing, I wanted to see if the company had been able to build upon its new resources to improve its equipment. I was also simply avid to audition another tube amplifier, a pursuit that I’ve been following with some assiduity in the past year. Tube amplifiers that I’ve listened to at some length in recent months include the VTL Siegfried monoblocks, the Audio Research Reference 75 stereo amplifier, the Octave MRE 220 monoblocks, and the Doshi V 3.0 monoblocks. The Siegfried had a mesmerizing fullness of sound and stygian bass and the ARC a pellucid treble. The Octaves had a very transparent sound and the Doshis a winsome musicality. What would BAT bring to the table?

Quite a lot, as it turned out. Apart from superlative reliability, chief designer Khomenko focuses on a low noise floor, purity of power, and a mellifluous sound. He’s gone to heroic lengths in designing the Rex preamplifier, which boasts no fewer than 18 tubes. Upgrades from its first incarnation include replacing the Six-Pak of capacitors with amorphous-core output transformers. The Rex has only one gain stage for signal purity and uses no global feedback. Its ability to drive low-impedance loads is also superb, deploying for high-current delivery no fewer than eight 6H30 tubes, which hail from Russia. The outboard Power Module, housed in a full-sized chassis, contains what BAT terms a low-impedance local power supply. The Power Module is a true dual-mono design that eschews silicon diodes in favor of vacuum-tube rectifiers. The AC shunt regulators are also built from vacuum tubes, for a total of ten tubes in the Power Module.

Meanwhile, the Rex II amplifier is hardly less impressive: it features a fully symmetrical triode circuit, employs auto-bias, and is monitored by an electronic protection circuit. It looks almost impossible to damage these big boys, a big change from the days when turning a tube amp on and watching whether it would perform or emit a shower of sparks was a big question mark.

Perhaps most startling, BAT doesn’t rest content with the possibility of powering your speakers with just a pair of its monoblocks. Instead, there was literally a colossal amount of BAT amplification in my listening room—four power amplifiers to be precise. The way BAT has designed its amplifiers, which are each based around two pairs of the extremely robust 6C33C tube, it’s possible to daisy-chain them—pretty much infinitely, depending on your tolerance for heat and your willingness to countenance a whirling electric meter that might even take off like a flying saucer. Essentially, if I have it right, the second amp, which was tied to the first amp, functions as an extra source of reserve power. Specifically, adding the second amplifier in parallel doubles the voltage, doubles the current, halves the output impedance, and increases the signal-to-noise ratio by 6dB. The idea is that it will provide an increase in soundstage size and musical control.

This is the mode in which I first listened. As a result, the immense power and grip of the BAT amplifiers when coupled with the Rex II preamplifier instantly came to the fore. One of the things that most impressed me in listening to baroque and early classical music was the iron grip that the amps exercised on the bottom end. It wasn’t that the amps had the opportunity to deliver pounding bass. On the contrary, it was the way they brought out the hitherto barely audible and subtle details of the basso continuo, thereby perceptibly enhancing the sense of the room in which the recording originally took place.

As enjoyable as it was to listen to two pairs of tube amplifiers, I have to admit that I cracked pretty soon. The heat, even in my fairly large room, was simply too overwhelming. But I also couldn’t help wondering if the additional complexity of the quad-amplification system might also not carry some sonic penalties as well as assets. For example, I couldn’t avoid the sense that a very slight muddying of sound was taking place with extra sets of speaker cables and interconnects linking the amps. Thanks to the generosity of the Nordost Corporation, I had oodles of its superlative Valhalla II cabling on hand for the review. But perhaps four amps were too much of a good thing: with a single pair of monoblocks the musical presentation took another notch up in alacrity and spontaneity and coherence.