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Reviewer: Frederic Beudot
Digital Source: Esoteric X-03SE
Analog Source: Acoustic Solid Classic Wood, AS WTB211, Grado Reference Sonata 1, Denon DL103, Clearaudio Nano, Esoteric E03 [on loan]
Pre-amplifier: Wyred 4 Sound STP SE
Amplifier: Genesis Reference 360, McIntosh MA2275
Speakers: FJ OMs, Rogers LS 3/5a, Zu Essence
Cables: Zu Varial, Zu Libtec, Esoteric Mexcel 7N-DA2100 balanced interconnects [on loan]
Power Cords: Zu Mother
Powerline conditioning: Isotek Nova and Titan [on loan]
Sundry accessories: Isolpads under electronics, ASI resonators and sugar cubes
Room size: 21' x 13’ x 7.5'
Review component retail: $7,500

If you've read my review of NAT's superb Symmetrical preamplifier, you already know about the company, its creator and just how impressed I was with the pure musicality of the Symmetrical. Unfortunately a few operational oversights stood in the way of bestowing our Blue Moon award to this fully balanced twelve-tube wonder which from a pure performance perspective fully deserved it. I've since been told that some of the small but pesky issues I’d noted have been addressed and that silent relays for the volume control are now standard. I can only encourage anybody looking for a very high-end balanced tube preamplifier at a not yet unreasonable price to go and give it a listen. But let me jump to the true star of today, the Signature Phono preamplifier, last but certainly not least in my half-year journey through various phono preamplifiers.

In many ways it was déja-vu all over again not only because the enclosures of the Symmetrical and Signature Phono are closely related but because the Signature Phono sounds spectacular whilst suffering tiny operational flaws - nothing dramatic that will prevent tremendous enjoyment for most but certainly a few practical elements that do not live up to comparisons with the cheaper Esoteric E03 or Audia Flight Phono.

As its name indicates, the Signature Phono is a phono preamplifier which will amplify the minuscule signals generated by MC or MM cartridges and apply RIAA equalization before passing the recorded data to either an integrated amplifier or line-level preamplifier. In all fairness, the question ‘what is it’ remains quite legitimate considering the huge size (19” x 22” x 5.7”) and weight (60lb) of the Signature Phono. It dwarfs more than one integrated amplifier which came through my music room over the years and certainly wins first place on heft amongst phono preamplifiers, besting even the Esoteric E03 which is no small piece of metal. Just for fun I included the above photo of the smallest phono stage I reviewed (the Clearaudio Nano) and the biggest (the present NAT Signature Phono) one atop the other. To reassure prospective buyers, the 20 x difference in price can also easily be heard.

Although the Signature Phono has two separate sets of inputs for MM (or high-output MC) and low-output MC cartridges, it should really be considered a single-input phono stage. The reason is quite simple. While those 2 inputs sport separate RCA connectors, choosing one or the other is done through a small inconvenient switch on the back of the unit. More annoying still is how the resistive and capacitive loading options for both inputs are selected by changing the same set of dip switches - again on the back. In practice this means that if you change from MM to MC—or run two tone arms—each time you change from one cartridge or arm to the other, you will need to dive behind the huge beast and reset the switches. To make matters worse, those dip switches are far recessed and their opening is quite small. Even those willing to go through this exercise will find it particularly unpleasant and knuckle-scratching unless they're equipped with the slimmest of fingers (I could not get mine through that opening and had to use a small screwdriver to trip the switches). For all intents and purposes then, this phono preamplifier should be considered a single-input affair that is radically impractical for anyone wanting to listen to more than one pickup on a regular basis. In and of itself that’s not a flaw, just something to be aware of and somewhat surprising amongst high-end phono preamplifiers which typically offer easier ways to handle multiple input adjustments.

That said and with the small percentage of multi-table, multi-arm, multi-cartridge listeners warned, this situation may actually be a blessing for the rest of us who run a singular vinyl rig. Once set up properly and left alone, this phono stage is pure musical bliss. It removes the temptation to go and fiddle with the settings every few minutes as might be the case with other components. For the few who need more flexibility, the Esoteric E03 or Flight Phono provide two truly independent inputs which can be either MC or MM with separate loading options that are far more accessible than the NAT (the jumpers on the Flight Phono are more practical than the switches on the NAT but neither come close to the convenience of the relay-activated load settings of the E03 whose rotary controls are on the front panel).