A lot of us who dig tube guitar amps also have a thing for vintage tube hi-fi gear. And while tube-powered receivers and integrated amplifiers from the golden age of tube technology are still available and relatively cheap, most of the stuff is way too bulky to be compatible with today’s ultra-portable audio and DVD players. Effects maker Z. Vex has come up with a solution for those who dig warm tube sound, but want it in a smaller package—one that can easily be carried along with an iPod or DVD-enabled lap-top computer and a small pair of speakers. It’s called the IMP AMP ($699 retail/$599 street), and it is the world’s smallest all-tube hi-fi power amp. Housed in the same compact aluminum enclosure that Z. Vex uses for its effects, the stereo unit looks like a miniature vintage power amp and delivers 1 watt per channel into 12 ohms (.75 watt per side @ 8 ohms). Power is via a pair of tiny, military surplus Phillips 6021W tubes—originally designed for missiles, these super-rugged d
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The IMP’s I/O complement consists of RCA-style input jacks and a pair of full-sized terminal blocks for connecting the speaker wires. The unit is powered by a 12-volt AC wall-wart supply, and it boasts a frequency response of 10Hz to 20kHz. The impressive sub-frequency response is due to the IMP’s DC-coupled circuit, which uses no capacitors in the signal path. The IMP has no controls other than two screwdriver accessible trimpots on the bottom, which allow you to adjust the input sensitivity in order to accommodate the output levels of everything from iPods to pro studio gear. As with most power amps, cosmetics are minimal, but a pair of LEDs cast blue light up into the front acrylic panel when power is applied.

I’ve been using an IMP in my office for quite some time, and I consider it one of the coolest pieces of tube gear I’ve tested. Connected to my Apple laptop and various pint-sized speakers (from Blue Sky, KLH, and others) the IMP consistently delivers warm, rich sounds that offer impressive clarity and bass response. The 1-watt rating is minimal for sure, but we’re talking tube power here, and this little head kicks out surprising volume while staying tight and dynamic—even when cranking on heavy rock material. The IMP never sounds strained or headroom challenged, and whatever small amount of distortion occurs seems to enhance the sense of presence throughout the frequency spectrum—sort of like an aural exciter.

In a world where downsizing is the trend (fast-food outlets notwithstanding), the IMP is the perfect solution for those who embrace the MP3 format—perhaps grudgingly—but want that extra measure of richness and vibe that only tubes can deliver.