Zesto Audio is a relatively new company located in Los Angeles where it manufacturers a full array of excellent tube audiophile equipment to bring music to life in the home. Though not priced atmospherically like many of its all tube competitors, it strives to surpass the finest gear available using smart technology, extraordinary transformers and parts, and pure genius from one George Counnas who just may be the best electronics designer and engineer in the world today. His new tube DAC, called the Athena, took 18 months of development in order to utilize and maximize a brand new chip from Japan called the ROHM. The rest of the unit utilizes a variation of the input and output tube stages and transformers of the Zesto Audio Leto Ultra II Preamplifier which is my current reference unit.
Loaded with features that maximize any digital feed includes as follows:
- Bit perfect: Native with No Up-Sampling: The Athena DAC maintains the original integrity of the audio signal, ensuring a true-to-source experience.
- Noise-Cancelling Tube Analog Output Circuit: The soul of the Athena DAC lies within its ability to cancel noise, delivering the most musical listening experience.
- No Filters on the Output: All filtering is done through the tube output circuitry with minimal phase shift, creating a better stereo image and black levels. This is the perfect merging of solid-state and tube technologies!
- Proprietary Grounding Scheme: Our innovative design effectively isolates digital noise, providing a clean signal that enhances listening pleasure.
- 4-layer copper Printed Circuit Board for extensive noise reduction.
- Adjustable Ground Switches: Easily eliminate ground loops to remove hum.
- No Negative Feedback: Our design philosophy ensures that your signal is neither limited nor compressed, allowing for dynamic expression.
- Dedicated 12AU7 Output Tubes: Engineered to drive true differential balanced output transformers for significant noise-cancellation.
- 12DW7 Input Tubes: This tube handles the input as well as drives the output tubes. The 12DW7 is fast, musical, dynamic, low noise, and offers exceptional sound quality.
- Controlled 2nd-order Harmonic Distortion: With a focus on sound quality, this feature is widely regarded as more musically pleasing.
- Zesto's exclusive ESP Supply: Anticipates the power needed and does not limit the music's ability to pull all the power it needs. Optimized for the tube output circuits, these power supplies further enhance the overall performance of the DAC.
- 12 Internal power supply/regulators on the DAC board
- Hidden Knob Feature that changes the slope filter from slow to fast
- Wide Range of Formats up to 32-bit/384kHz files
- 4 DSD Sample Rates: X1 (64), X2 (128), X4 (256), and *X8 (512)
- *X8 both the X2 and X4 DSD LEDs will Illuminate
- 3 Bit Rates: 16, 24 and *32
- *32-bit rate will illuminate the 24-bit LED
- 8 PCM Sample Rates: 44.1, 48, 88.2, 96, 176.4, 192, 352.8, and 384
- DAC will be upgradable for future technology
My Ideal DAC
I have been truly searching for a DAC that uses an innately musical chip like the Wolfson chip manufactured in England but with the sophistication to handle very high resolution sources and with no upsampling. Solid-state DACs I have auditioned have left me cold, literally, and just will not give me that truly musical textural definition. Current tube DACs are just the opposite; warmly colored with sluggish nuances. I want neutral, lively, and realistic—like a terrific phono cartridge or as close as I can get.
The Reference System
- Speakers: Marten Birds with Bybee Golden Goddess Filters on the Tweeters/Midrange
- Preamplifier: Zesto Audio Leto Ultra II Preamplifier
- Amplifiers: E.A.R. 890 (two units in mono)
- DAC: E.A.R. DAC 4 and Transport
- Phono: Zesto Audio Andros Deluxe II Phonostage
- Turntables: E.A.R. Disc Master Magnetic Drive Turntable; EAT Csharp Turntable
- Cartridges: Grado Epoch III, Acoustical Systems Archon MC, London Reference MM
- Tuners: Marantz 10B, Day Sequerra FM Reference, McIntosh MR80
- Interconnects: UITaudio.com RCA and XLR, UITaudio.com Active USB, and S/PDIF.
- Speaker Cables: Jorma Origo Biwire
- Phono Cables: Jorma Origo, Cardas Clear Beyond
- Transports: Pioneer Laser Disc Player; Allesis Masterlink, Two Terrabite Drive
- Room Acoustics: SteinMusic Schumann Generator, SteinMusic Silver Reference Grounding Block, SteinMusic Schumann Grounding Block, SteinMusic Acoustic Discs
Specifications
Inputs
- One USB
- Two Optical (S/PDIF)
- Two RCA Coax (S/PDIF)
- One AES/EBU
- One I2S (see page 8 for diagram)
Outputs
- Class A, Dual Mono vacuum tube output stage
- No filters on the tube output stage
- One set of true XLR transformer Balanced outputs (pin 2 hot) with an impedance of 300 Ohms
- One set of Single-Ended RCA outputs with an impedance of 300 Ohms
- Maximum peak output level of 3 Volts RMS
- 2 Independent ground lift switches on the left and right outputs
- Recessed RCA and XLR output connectors are gold-plated with an isolated ground.
- No negative feedback
Digital Performance
- State-of-the-art, most musical ROHM DAC chip
- 4-layer copper Printed Circuit Board
- PCM up to 32‐bit/384kHz
- DSD64 (X1), 128 (X2), 256 (X4), 512 (X8)
- Native no up sampling
Vacuum Tubes
- Two (2) Gold pin JJ ECC82/12AU7
- Two (2) Gold pin JJ ECC832/12DW7
- High-quality gold pin ceramic sockets
Detailed Specifications
- Frequency response: 10Hz to 20kHz
- Non-inverting output polarity
- Cross talk: >90dB
The Performance Comparison
Let me begin by saying that Zesto Audio creates equipment with features no one else has to my knowledge. Every main line Zesto Audio item has dual ground switches to maximize quiet. Even this DAC has dual switches so you may float either or both grounds if necessary. I have never seen this on a DAC. Most all tube DACs are Class A like the Athena, but are they all zero feedback for maximum definition and zero compression? The Athena is fully balanced compared to balanced DACs that just give you quasi balanced outputs with no purity advantage over the single-ended outputs. The back end tube section is extraordinary taken from the Zesto Audio Leto using the amazing 12DW7 tube—half 12AX7 and half 12AU7. A true stroke of designing brilliance reducing the tube circuitry by a third. There is much more to discuss, but I believe the proof is in the pudding so here we go.
My reference DAC from Tim de Paravicini is ten years old this year. I have retubed it with four gold pin JJ ECC88 tubes checked and matched. The powercord is the cutting edge UITaudio.com Active Power Cord that turbo charges every amp, preamp, DAC, or accessory it may be used with. Interconnects are the balanced UITaudio.com Interconnects and most of the digital wires are sourced from UITaudio.com. The E.A.R. DAC 4 was on a Townshend Seismic Sink. I make it a policy to not compare brands unless the gear is discontinued and no replacement is on the horizon. The E.A.R. sold for $13,000 with a transport a decade ago and the Zesto Audio Athena sells for $15,000 now. They have similar general concepts authored by two geniuses an ocean apart.
The E.A.R. DAC 4 is an upsampler, taking all PCM resolutions up to 24/192. 24/192 plays native. It utilizes a separate chip for single DSD only. The Zesto Athena plays only native at all resolutions and is capable of up to 8x DSD from the same ROHM chip. So goes progress. Tim preferred the 6DJ8 tube variant while George prefers the 12 volt tube variant.
In direct comparison the DAC 4 has less definition and clarity overall. Ten years have brought a lot of progress to the DAC world. It has withstood competition because there just are not any tube DACs I have heard that compete with the DAC 4 until now. Solid state DACs just do not have the musical texture I crave.
Focusing on the Athena, I tried software from Roon, Audirvana, and J River. All worked perfectly glitch free. Utilizing Roon, I listened to Yuko Mabuchi Trio, Yarlung Records, single DSD. I specifically listened to Saint Thomas by Sonny Rollins for each test. It was lively, very open, extremely dimensional, very good depth, and very realistic. The clarity of the recording was stunning.
Switching to the same Yarlung Recording in double DSD, the piano had more weight and definition. There was more air and separation plus the depth was enhanced. The drums had more weight and the overall musical sound was more sophisticated.
Switching to quad DSD for the same recording, I noted added punch and drive, greater depth to the drum set, and overall greater definition. In quad DSD with the Athena, the Yarlung Record sounded like a master tape or a very high-end LP. Amazing! Native DSD of France stocks lots of quad DSD albums.
Checking out the Athena's switching facilities, I listened to New Amsterdam Voices, Short People, on of the few cuts I have in 8x DSD and 24/96. Switching between the two sampling rates was quiet and flawless. The 8x DSD was vastly superior and was earth shatteringly realistic and alive.
The album The Visual Sound, Where You Are My Love selection, I first listened to 24/352.8. I do not know the source of this one but it sounded very juicy and analogue. The violin was a bit bright lacking rosin.
The Visual sound in double DSD was more elegant and better focused. Tons of definition were revealed with a snapier pacing. The Visual Sound in 8x DSD had even more presence, more clarity in the background, and a more elegant violin and guitar sound.
Next up was the Tchaikovsky First Piano Concerto in single DSD with Van Cliburn. My impressions of the recording on the Athena were lots of clarity and warmth, a powerful presentation, sweet mellow violins, and very realistic soundstaging overall. A you are there recording with great focus to every instrument. There was dramatic black space between instruments and a complete lack of noise of any kind. This was state of the art performance from the Athena.
I then listened to the Sibelius Violin Concerto with Heifetz, Chicago Symphony, 1959 on single DSD. It was most excellent and realistic as well. The violin was perfection with extraordinary clarity. Definition front and rear was better than I have ever heard it.
Scheherazade, Reiner conducting the Chicago Symphony, RCA, was played in single DSD. This was truly elegant mellifluous sound. The was no edge or distortion, just purity. The overall presentation was musical, warm, neutral, and clear. The bass was authoritative and fully enhanced with textural nuances. The presentation was involving to the max and with endless power. The Athena truly brought out the best of this historic recording.
I listened to the Royal Ballet, Ansermet conducting, RCA, on single DSD. A truly famous historic recording made even smoother and more detailed by the Athena. The dynamic range was superb, the harp was so very realistic, and the musical textures were extremely analogue.
I heard my very favorite cello concerto recording, the Dvorak, Starker, LSO, Dorati conducting on Mercury in single DSD. I am accustomed to this being a bit strident but no more! It was most realistic with silky smooth violins. There was more rosin on the cello sound and no peakiness at all. The Athena produced the most authoritative presentation I have ever heard. The orchestra was in the room.
I listened to the Rachmaninov Piano Concerto Number 2, Mercury recording, on single DSD. A gorgeous recording which was truly better than I have ever heard it. The piano was tightly focused and very natural and beautiful with awesome weight and authority. The presentation produced a huge soundstage with spacious quiet between instruments. The sound was uncompressed with definition galore. Finally, dynamic range was huge!
I was curious about trying a Reference Recording SACD on the Athena so I selected the Beethoven 5 and 7 Symphonies, Honeck conducting, Pittsburgh Symphony recording. The Athena spread the soundstage out wall to wall. I loved the sound of the horn section which was clear and correct. I heard gorgeous tonality with very powerful dynamics. This is a killer recording.
I should mention the included slope filter for Red Book CD which changes the filter slope from slow to fast. It is activated by depressing the digital input knob giving you a light show of either fast or slow lights. This is very cool. I tried this on numerous CDs and preferred the slow slope every time. You may choose otherwise and enjoy.
CDs were more detailed and less distorted on the Athena than the DAC 4. Foreground and background clarity increased with the Athena as did instrument weight and slam. I still enjoyed CDs on the DAC 4 but they were more present and alive on the Athena. The higher the resolution the better the performance of the Athena compared to anything else I know of.
Though tube rolling is certainly acceptable, I found the performance of the Athena so dialed in that tube rolling became unnecessary. You will only dull the performance of the Athena with NOS tubes. I believe this is only the second tube piece I have auditioned where tube rolling did not improve the performance.
Summary
After throwing every kind of music and connection I could muster including USB, S/PDIF, and AES/EBU, I was unable to make the Zesto Audio Athena DAC with ESP Power Supply do anything but perform to state of the art levels. I have never heard a DAC this alive, lively, and realistic with such extraordinary definition. The level of quiet between instruments is perfection. Switching between bit rates is without flaw. The lights on the front panel clearly show you what is playing. I love the analogue knob dialing in the clearly marked digital sources. I have not heard a DAC on the planet that exceeds the Athena's performance, tube or solid-state. I go to the symphony to hear the real thing and that is what you will hear with the Athena DAC. I heartily recommend you call your Zesto Audio Dealer and audition the Zesto Audio Athena DAC with ESP Power Supply ASAP.
Zesto Audio Athena DAC with ESP Power Supply
Retail: $15,000
Zesto Audio
805.807.1841
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Carolyn Counnas
