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With female voice, the ability to play 'you are there' recordings like Anne Bisson’s Blue Mind [Fidelio Music] produced a startling lifelike quality that bordered on the holographic. It offered the continuity and seamless flow only tubes can provide although the solid-state crowd might argue the point. One of my older Audio Research tube amps was lush and beautiful. Every record played was beautiful. But not every record is beautiful. Brass is not beautiful; rock is not beautiful. It was an alluring sound but ultimately not satisfying. This recall caused some initial concern about the DXL with their T-1610 triodes. That worry was misplaced. Yes you get that all-important midrange magic which is beautifully organic, gorgeous of color, rich and grain free but you would never call it romantic or colored.

Dynamics. How did the 'zillas handle one of the most dynamic torture tests, Dave Brubeck's Take Five, Time Out [Dave Brubeck Quartet, Classic Records] or some classic rock like "Burning Down the House" from the Talking Heads' Stop Making Sense [EMI Records]? Though vastly different, both have lightning-fast transients and huge dynamic swings. Throughout each there was no smearing between initial transients and the body of the note, and both produced dynamics that almost had me jump.
Images were solid and stable regardless of level and musical density. To dig deeper into congestion, try Reiner’s Festival [Chicago Symphony, Class Records 45 Series]. Delineating string instruments from out of the mass of violins, cellos and double basses clearly defines the best from the mere contenders and the Krons were one of the best with virtually no congestion at complex and high levels. The DXL were deal silent too, with no microphonics or hum but just a silky backdrop. The snap of drums, the delicate air of a shimmering triangle or chimes from "Glass Dolphins" on John Klemmer's Touch [Mobile Fidelity 1-006] floated on nothingness.

Silence is an element of music and should be portrayed as such, not as grey grungy matter. This was as good as I’ve heard from tubes, with only the best transistors offering deeper blacker backgrounds. It's not just about what's there but also what's not - hardness, electronic haze, artificial coloring. The word 'organic' constantly migrated to my listening notes. Lower treble energy sometimes masquerades as liquidity. Not so with the Kronzillas. Although not matching the virtually limitless extension of the Tenors or darTZeel, their top end was extended and continuous, natural with neither enhancement nor rounding of the leading edge. Instruments appeared in space with an almost physical reality which drew me into the music.


Demerits. Negatives? Virtually none which depends somewhat on your focus. As good as the Kronzillas are, if your number one priority is the deepest bass with ultimate control, transistors might have your vote. For musicality, emotion and a total commitment to harmonic accuracy, the DXL belongs on your high-end short list.


Comparison. I had three state-of-the-art contenders in the room: darTZeel 108, Tenor 350M and Kronzilla DXL. Having lived with traditional push-pull amps (VTL S400s) and OTL (the original Tenor), I have a moderately good sense of the differences. The perfect amp—or any perfect component for that matter—doesn't exist. Each has strengths and weaknesses. For pure tube-based amps, the VTL Siegfrieds along with their smaller S400 stereo sibling offer amazing top-to-bottom slam and dynamics which probably exceed the DXL. VTL’s dynamics are prodigious but the Krons are not outclassed. Where the Kronzillas excel is that wonderful midband where the majority of music occurs. The Krons offer slightly more of that organic magic, the VTLs display a little more forward excitement. Different routes to the same end. The DXL compare very favorably with OTL sound as both have an essential purity and seamlessness I find alluring. Where they diverge is that the DXL operates in the real world. It's designed for real-world speakers at realistic volumes. The Kronzillas also have better bass control. Since the VTL monos and Tenor OTLs have been out of my system for a few years, I am relying on memory which can be dangerous. But both were long-term reference amps so I have a pretty good sense of their capabilities.

Compared to the darTZeel, the Kronzillas have a warmer richer sound with better decay. The 108 has a more extended treble and better micro detail. Although quite different, both convey the musical experience. As to the Tenor 350, at more than twice the price of the Kronzillas it's a somewhat unfair comparison. The Tenors are arguably one of the top amps in the world and my personal reference. Could the twin triode Kronzilla truly topple the reigning king and save us $50k in the process? Not. In the ultra high-end there's generally no free lunch. The Krons offered many of the Tenors' qualities including a seamless wide deep soundstage, tonal correctness and rich musicality. There were times when I thought that the Kronzillas met or exceeded the Tenors in a specific trait such are air, decay or imaging. But over longer sessions and significant comparisons the Tenors ultimately won out. Their bottom end, extension and resolution were clearly superior. As for a sonic checklist of attributes, the Krons came close but the Tenors were ultimately superior. This is no criticism but high praise. The fact that they held their own was amazing. If I had never heard the Tenors, I could happily live with the Kronzillas.

Conclusion. When I first installed the DXL I anxiously envisioned the virtues of class A triode sound with the hope and concern of true ability to drive a real-world system to concert hall and rock levels. They met these expectations and far more. They are reference quality, magical, seductive, dynamic and transparent with a holographic soundstage. At this level of exotic amplification and contrary to conventional wisdom, the design paths of great amps do not necessarily converge sonically. And that's good. Even those who claim utter neutrality can end up at different points on the musical spectrum. If you look for a unique visual statement and a piece of musical art, the DXL deserves an audition with those who demand the best. That just about sums up the Kronzillas – a stunning visual and sonic statement that takes its respected place in the world of state-of-art tube amplifiers.
 
The author has also published this review in video format for AVShowrooms.com.

Specifications
Type: monoblock single-ended tube amplifier operating in pure class A, zero feedback
Frequency response: 20Hz to 20kHz (-3dB)
Power output: 100 watts RMS (THD=3%)
Output tubes: four T1610 (two per mono)
Output impedance 4 or 8 ohms
Input sensitivity:1V RMS / 47kOhms at 100W
Dimensions: 38.5 x 41.5 x 55cm WxHxD
Weight: ~80lbs each


KR T1610 tube
Low frequency ultra high-power direct-heated triode
22-50 watts of pure class A power
Maximum plate voltage 650V
Maximum plate current 250mA
Plate dissipation 150 watts
Va 400V
Ia 160mA
Vg -83V
Transconductance 9.9mA/V
Amplification factor 3.7
Filament voltage 5V (DC/AC)
Filament current 3.8A
Price: $2.590/ea.
KR Audio website