Reviewer: Marja & Henk
Financial Interests: click here
Sources: PS Audio PWT; Dr. Feickert Blackbird MKII/DFA 1o5/Zu DL-103; Phasure XX-PC;
DAC: Phasure NOS1 DAC; PS Audio Direct Stream DAC [loaner]; PS Audio NuWave DAC [loaner]
Streaming sources: XXHighEnd; iTunes; Devialet AIR; La Rosita Beta; Qobuz Desktop, Tidal Desktop
Preamp/integrated/power: Audio Note Meishu with WE 300B (or AVVT, JJ, KR Audio 300B output tubes); dual Devialet D-Premier; Hypex Ncore 1200 based monoblocks; Trafomatic Kaivalya; Trafomatic Reference One; Trafomatic Reference Phono One; Music First Passive Magnetic;
Speakers: Avantgarde Acoustic Duo Omega; Arcadian Audio Pnoe; Podium Sound One; WLM Sub 12; Sounddeco Alpha F3; dual Zu Submission MKI; Soltanus Virtuoso ESL
Cables: complete loom of ASI LiveLine cables; full loom of Crystal Cable cables; full loom of Nanotec Golden Strada; Audiomica Pearl Consequence interconnect; Audiomica Pebble Consequence;
Power line conditioning: PS Audio Powerplant Premier; PS Audio Humbuster III; IsoTek Evo 3 Syncro; AudioMica Allbit Consequence
Equipment racks: Solid Tech and ASI amplifier and TT shelf
Indispensable accessories: Furutech DeMag; ClearAudio Double Matrix; Franc Audio Ceramic Disc Classic; Shakti Stones; Akiko Audio sticks; Kemp polarity checker
Online Music purveyors:,,,  
Room treatment: Acoustic System International resonators, sugar cubes, diffusers
Room size: ca. 14.50 x 7.50m with a ceiling height of 3.50m, brick walls, wooden flooring upstairs, ca 7 x 5m with a ceiling height of 3.50m, brick walls and concrete floor downstairs.
Price of review item:  €9'000 depending on taxes and shipping

Electron tubes. Vacuum tubes. Glow bottles. Thermionic valves. Can one ever have enough? Honestly, we don't think so. There's magic in a system where all possible components use tubes. In our own inventory you will find a lot of tube gear. We regularly swap things around not only as components but by getting involved in heavy tube rolling. Why? Not only because we can. It's mostly because the result can be much more intense enjoyment of the music. Even in the current digital age where analog media—yes, that includes CD—are becoming obsolete and musical content enters the home via glass fibre or copper telephone wires in true digital format, feeding this signal post analog conversion to a tubed rig offers more satisfaction. It's the best of both worlds. Digital offers the convenience of delivery but little room for personal adjustment. Adjustment to personal taste is grand with tube gear. Take our Audio Note Meishu. Basically it's a simple 300B SET design with two easy adjustment options. For the two output bottles, we can make a selection from our 300B spice rack. Do we want the airiness and feather-light operation of a Western Electric; or the more robust results of a KR Audio variant? Then there's the 6SN7 in the driver stage. This acts as the fine-tuning dial. There are still very interesting NOS samples of this tube to market and at reasonable prices. The fact that the 6SN7 is a double triode and used as such by the Meishu eliminates sometimes difficult pair matching.

To go tube all the way, we turn to our trusty Dr. Feickert Blackbird turntable hooked up to Trafomatic's Reference Phono One. One step further feeds the latter's output to our Trafomatic Reference One preamp, from there to the pre-out of the Audio Note Meishu. Here we remove the 6SN7 driver so the pre-out becomes an input to the power stage. The glorious output of a fraction of a 300B's six watts is more than enough to fill our not small room with beautiful emotion-laden music. Admittedly, our speakers are of the high-sensitivity genus by ranging from 100dB to 109dB. When asked if a review of a new integrated tube amplifier might be up our alley, we were instantly curious to learn what kind of amp it might be. The first thing to learn was being fitted with KT120 rated at 150wpc. Ouch, that was a ton of power - tube power that is. In a paper researched and published by Peter van Willenswaard, tube power is different from transistor power. In brief, what a 6wpc 300B SET can do in terms of output voltage at the speaker terminals is equaled only by a 50wpc transistor amplifier. In the same vein, with highly sensitive loudspeakers, only the first two or maybe three watts matter. Thus an amplifier with superb behaviour on noise, distortion and linearity can work well into hi-eff speakers even when capable of far more power.

Fortunately the specifications of the proposed NVO ISA-2 promised exactly what we wanted at this stage of due diligence. Here's what made us happy. Frequency response @ 1W is a whopping 5Hz to 250kHz +/- 0.5dB. These are numbers we learned to value during our previous review of the Maraschino Cherry amps. Equivalent bandwidth even led to us to add a super tweeter to our hornspeaker setup. Check. Total harmonic distortion @ 1W is rated at 0.02%. Check. Needless to say, at full blast both numbers will change. Frequency response then narrows to 20Hz-40kHz, THD increases to 0.15%. We'd simply never encounter these values. Our mental sanity, ears and speakers—and in that order—are too precious. Based on these specifications and concomitant promises, we agreed to do the review. Srajan could start the administrative settlement. Not long afterwards, a huge wooden crate arrived. The box had no markings or logos, just the DHL shipping papers.