NAT Symmetrical line preamplifier test review

Robert J. Reina (Stereophile) writes:  Sometimes, a product review in Stereophile can breed additional reviews. Shortly after I reviewed the Audio Valve Conductor line stage in the July 2009 issue (Vol.32 No.7), I was contacted by NAT's US distributor, Musical Sounds: "Hey, if you liked the Audio Valve Conductor [$13,995], you'll love the NAT Symmetrical line stage at $8000! Would you like to review it?" Aside from Michael Fremer's review of the battery-powered NAT Signature Phono stage in the July 2007 issue, I was unfamiliar with this Serbian maker of tube electronics. But "Sure," I replied; "why not?"

Dejan Nikic has designed tube electronics for NAT Audio since 1993. Their current product line consists of three tubed preamplifiers, a tubed phono stage, five tubed monoblock power amplifiers, a hybrid integrated amp, and three power cords. The visually striking Magma, a single-ended, class-A monoblock, uses a single TH450 tube and costs $45,000/pair. NAT claims that this amplifier, at 160W, is currently the most powerful single-ended amplifier ever made to use a single tube in its output stage. At $8000, the Symmetrical line stage is not the most expensive preamp in NAT's product line; that honor belongs to the dual-chassis Utopia line stage ($9000).

The Symmetrical's dual-mono, fully balanced circuit includes 12 tubes (6 per channel) operating in pure class-A triode configuration with zero loop feedback. The signal path for each channel has a ...............