In 1976 a Soviet MiG-25 interceptor made an emergency landing in Japan, and when the US Air Force took it apart, it found a large, heavy triode tube regulating the power supply for the jet's radio. Alex Halberstadt of Stereophile tells that story to introduce the 6C33C, the tube BAT is best known for. It handles a lot of current, so it can make serious power without an outsized output transformer. Everything BAT builds is fully balanced, which means each channel travels as two mirror-image copies of the signal, and noise that gets into both copies cancels out, BAT says. Halberstadt called the VK-80i "quite possibly the most neutral-sounding tube amp I've heard," and Dick Olsher of The Absolute Sound found it "free from the usual tube-amplification colorations." BAT's tube amps set their own bias, and BAT's view is that "The best-sounding fuse is no fuse at all." BAT suits listeners who want tube tone without bias adjustments or fuse changes.

The two integrated amplifiers are the usual way in. The VK-80i is all tube, with 55 watts a channel, and the VK-3500 pairs a tube preamp stage with a solid-state power stage and a built-in phono stage. Mark Craven of Hi-Fi News found the VK-3500 livelier, with more headroom, and the VK-80i surer with tone. He says the tube amp "gallops like a thoroughbred," and he heard it do better with sensitive Monitor Audio floorstanders than with his B&W standmounts. Marc Phillips of PT Audio called the VK-3500's phono stage "one of the finest inboard phono stages I've heard." The VK-80i has three sets of speaker taps. BAT's rough guide is that the low taps give firmer bass and the higher ones a more open sound, and Olsher calls it vital to experiment. Use the balanced inputs if you can. Foo Marn Hing of AudioFi moved his VK-3500SE to its XLR inputs and heard the noise drop "to a stunning naught."

Victor Khomenko grew up in Leningrad and built his first reel-to-reel tape recorder at 10. He arrived in Wilmington, Delaware, in 1979 with $400 to his name and joined Hewlett-Packard, where Steve Bednarski was a colleague. When Bednarski said he had bought a preamp with a balanced circuit, Khomenko replied, "That's the only right way to build a circuit." For BAT's first power amp, the VK-60, he judged the KT88 and 6550 not linear enough and ruled out big transmitter triodes for their lethal voltages, which led him to the 6C33C. The VK-60 and the VK-5 line stage launched BAT at the 1995 CES. The VK in BAT's model names is Khomenko's initials. BAT says it still hand-builds everything in its own US factory. The flagship is the solid-state REX 500, which uses only one type of output transistor so both halves of the waveform pass through identical devices. Rogier van Bakel of Stereophile credited it with "grip that could embarrass a bench vice," and Craven called it "amplifier royalty."