Hyperion CS4397 tube DAC: owners’ reviews

Owners of Demograf Audio converters built on the Cirrus Logic CS4397 with a tube output stage describe deep, fast bass, high detail without glare and an ease they call “analogue”. Below we summarise posts written between 2013 and 2018 by owners of these units and by the designer, the design now offered as Hyperion: the sound by range, how it worked with loudspeakers and headphones, their comparisons with the NAD M51 and Yulong DA9, what DSD brought, and their reservations.

These impressions are summarised and translated from owners’ posts on an audiophile forum. They are the subjective views of their authors, not measurements or claims of Demograf Audio.

Which units the owners describe

Every unit in this article was built to order around the CS4397 with an EL8 tube output stage and a tube-rectified power supply in a separate chassis. Inputs, outputs and casework differed from owner to owner: some had USB (Amanero), one had a balanced output, one a faceplate finished to match the owner’s loudspeakers. One owner listed his unit’s design: a CS8416 S/PDIF receiver, an Amanero USB receiver with galvanic isolation, transformer coupling after the DAC chip on nanocrystalline cores, filters wound with Litz wire on nanocrystalline cores, EL8 tubes in class A without feedback, step-down output transformers with an output impedance of about 35–40 ohms, and the tube-rectified supply in its own box.

Today the same chip and output stage are offered as Hyperion: S/PDIF coaxial and USB (Amanero) inputs, a solid-state output stage as standard, and a tube stage on EL8, AL4, EF14, 6Zh4 or ML6 as an option.

Sound, range by range

Bass

• Owners mention the bass first. One describes it as deep and fast; another found it both well defined and genuinely deep, where his previous DAC never reached the lowest octave.
• For one loudspeaker owner the bass changed the character of his speakers so much that he dropped his plan to replace them or add a subwoofer.
• A listener who compared it with a Philips TDA1547 converter heard the CS4397 reach further down: “the low bass of the Cirrus is something else”.

Midrange

• One owner, after an upgrade of his unit, heard a slight colouring of the midrange disappear; he notes that he had noticed it only in direct comparison with a more neutral DAC.
• Violins and a string quartet impressed another listener most; he found the CS4397 ahead in detail, scale and frequency extension, and nearly level with the TDA1547 in natural timbre.
• A listener at a group session heard accents at some frequencies on that particular unit and would not call it a monitor, but found it engaging, especially on jazz.

Treble

• One owner singles out the absence of ringing: he hears none of the treble glare he associates with most delta-sigma converters, and no hint of sibilance. He adds that his previous DAC, a NAD M51, did not suffer from it either.
• Another owner almost got rid of sibilance on his Fostex TH900 headphones.
• The listener at the group session heard a slight tilt towards the treble on the unit he heard there.

Soundstage

• One owner heard the stage grow almost twice as wide once the DAC was in his system; music had already extended beyond the loudspeakers, and now it went much further.
• Another describes the stage as harmonious, soft and detailed after a converter that had sounded “needle-sharp” to him.

Resolution and detail

• Owners describe very high detail that does not come at the expense of body. One heard more detail than from his NAD M51 by a clear margin; another found that the DAC “plays nothing of its own”: a bright recording sounds bright, a bass-heavy one has its bass.
• The listener at the group session found the stage and detail good overall but would have liked finer microdetail.

Dynamics and music

• Several owners listen mainly to rock and metal. One calls the DAC a find for metal, with clarity in both the bass and the treble on brutal death metal; another chose it for progressive rock and hard rock.
• Others describe it as energetic without excess, with drive and good layering in depth.

With loudspeakers and headphones

With loudspeakers, owners describe the change as the larger one. One owner, who had listened to the built-in DAC of his CD player for almost fifteen years, says the glassy CD sound went away while clarity stayed, and the music flowed rather than stumbled. Another heard his speakers gain the deep, defined bass they had lacked.

With headphones the reports are more mixed:

• One owner heard his Sennheiser HD800 lose their slight brightness and gain much more bass.
• Another heard more impact on the Fostex TH900 and found the HD800 drew closer to them in bass, with a very wide stage and greater comfort over long sessions.
• At the group session, AKG, Beyerdynamic, Denon and Sennheiser headphones sounded bright in places through the same unit, while the loudspeakers sounded fine; the listener expected cable choice to solve it.
• One owner whose custom build had tube headphone outputs heard low-impedance headphones such as the Sony MDR-CD3000 and Audio-Technica ATH-W11JPN open up in space and detail when driven straight from the tubes. For high-impedance Sennheiser HD800 and Beyerdynamic DT911 he preferred a separate headphone amplifier.
• The owner of a revised unit wrote that it all but removed the slightly veiled character of his Audeze LCD-3. Another LCD-3 owner doubted that a DAC could change a headphone’s character so much: his sounded the same from three very different DACs and from vinyl.

Compared with other DACs

vs NAD M51

Two owners came from the NAD M51. One heard the CS4397 converter as more detailed by a clear margin, with defined, deep bass where the NAD had sounded mid-forward with looser, fading bass on his loudspeakers. The other heard bass, scale and detail from both, but more of each from the Demograf Audio unit, with a more analogue sound and no trace of a digital edge.

vs Yulong DA9

One owner bought a Yulong DA9 for his Sennheiser HD800 and skipped some tracks because the sound felt needle-sharp to him. With the CS4397 converter in its place, he describes the stage as harmonious, soft and detailed.

vs multibit converters

At the group session, the multibit converters on hand played more evenly and with a more singing quality, while the CS4397 converter pulled ahead in stage and detail. A listener who heard it next to a Philips TDA1547 converter together with the designer chose the TDA1547 for its natural midrange, but found the CS4397 ahead in detail, scale and bass extension, and planned a second DAC on it.

What owners report

One owner sent his unit back for a second revision and listed the changes: transformers on nanocrystalline cores, an Amanero USB input with native DSD, the rectifier upgraded to a Mullard GZ34, a reworked power supply with separated rails and galvanic isolation of the digital input, a new power-supply chassis, Yamamoto tube sockets, an adjustable filter, and a revised analogue stage with unnecessary parts removed. He heard a large step: more micro- and macro-detail, especially on complex progressive rock, better clarity and evenness across the range, more drive and a wider stage, with nothing lost in musicality or engagement.

Another owner asked for the faceplate to match the colour of his loudspeakers. The unit’s output level was so high that, with low-impedance headphones, his headphone amplifier was too loud on the first step of its stepped volume control. The designer proposed a level divider for that output, and after a revision with an output transformer the level matched his CD player’s.

A third owner had a custom chassis, a balanced output and USB built in. The drivers installed without trouble on Windows, and on a Mac it worked without any; he played music through Roon.

At a group session in an owner’s home, the DAC was added to a system with a CD player and a laptop. The listener liked that it matched the owner’s amplifier in style and that the controls were simple, but missed a balanced output for AKG K1000 headphones. Synchronisation with the computer was stable, and he heard no difference between transports.

DSD on the CS4397

In 2014 the designer described a new CS4397 board for the converter: separate power supplies, grounds isolated with ADuM chips, and operating modes managed by programmable logic, with DSD added to PCM. Comparing the same recordings, he heard DSD as noticeably cleaner and more detailed than PCM, and said the main remaining work was to switch between the two formats without clicks.

An owner whose CS4397 converter was upgraded with DSD spent a week comparing the same tracks from his SACD images as DSF files and as FLAC at 24-bit / 176.4 kHz. On every track DSD won for him in cohesion, purity, spatial and timbral resolution and overall believability. The difference was not huge, he writes, but it was clearly audible, so he began converting his collection to DSF.

Reported problems

• A slight treble tilt and some frequency accents on one unit, heard as brightness on several headphones.
• A very high output level on an early unit, brought in line after a revision.
• No balanced output unless ordered.
• A slight midrange colouring on a first revision, removed in the second.
• High-impedance headphones sounded better through a dedicated headphone amplifier than straight from the DAC’s tube output.

Summary

Owners of CS4397 converters with an EL8 output stage agree on deep, fast and well-defined bass, high detail without treble glare or sibilance, and a sound they describe as analogue and engaging. Rock and metal listeners are among its keenest owners.

The reservations concern system matching: one unit leaned slightly towards the treble, some headphones sounded bright through it, and high-impedance headphones did better with their own amplifier.

Which Demograf Audio piece fits

• Hyperion is the current converter on the Cirrus Logic CS4397: S/PDIF coaxial and USB (Amanero) inputs, Red Book over coaxial and up to 24-bit / 192 kHz and DSD256 over USB. The stock output stage is solid-state; a tube stage on EL8, AL4, EF14, 6Zh4 or ML6 and a tube rectifier are options, and balanced XLR outputs and further inputs are made on request.
• If you play mainly CDs and prefer a classic-chip presentation, the Reference Tube DAC is built on the TDA1540, TDA1541, TDA1547, PCM63 or PCM1704. Owners’ impressions of these chips are collected in our reviews of Aphrodite (TDA1547), Persephone (TDA1541) and Calliope (TDA1540).

Every converter is made by Dmitriy Gubchenko. Each is made to order and covered by a one-year warranty (extra warranty available: +1 or +2 years).