Review | Denafrips Terminator Plus DAC and Gaia D to D Converter

Loyal readers (Loyal Readers? Sounds like I think I’m a journalist or something!) may remember that last year, I got my hands on a Denafrips Pontus II DAC. At the time, it was, by far, the most detailed, cleanest and most musical DAC I had ever heard. And as good as it was, I decided to ask Denafrips to send me their flagship model, the $4000+ Terminator Plus (T+) and their premier D-to-D converter the Gaia. Well, I expected the T+ to sound somewhat better than the Pontus II (after all, it costs more than twice as much for the DAC alone), but I must say that I was not prepared for the level of difference. It’s one of those cases of “How much better could it be?” The answer, comes back, of course, that in spite of the fact that while I could not imagine “better”, it turned out to be a LOT better! It seems that technologically, there is much more to the depth and breadth of information encoded in a digital signal to be plumbed than many would expect and I suspect that we have barely scratched the surface of what’s available even in an MP3 digital stream, much less in high definition recordings!

Along with the T+, I requested the company’s flagship D-to-D converter, the Gaia, as well,. Together these two units tip the scale at more than US$8000! The reason that I don’t give a more precise price is because Denafrips lists their prices in Singapore dollars, and the conversion to US Dollars or Euros or Pounds Sterling fluctuates with the exchange rates. Now, I know that this is a lot of money, especially since a perfectly usable DAC, such as the Schiit Modi Multibit, (to which I’m listening on my computer desktop system as I write this) can be bought for just a hair under US$250. But keep in mind, that there are DACs from companies like MSB and dCS that cost (considerably) more than US$20,000. So, by comparison, a US$8000 solution is really not all that extravagant – relatively speaking. What matters is not so much the actual price as it is what you are getting for your money. And with the Denafrips Terminator+/Gaia combo, you are buying performance that I would not hesitate to compare to many of these stratospheric solutions from the likes of MSB, dCS and others. For this combo is certainly a world-class digital to analog solution!

Physical Descriptions

Terminator Plus (T+)

The Terminator+ is a large, full-component sized unit at: 430 X 380 X 105 mm (17” X 15” X 4”) and it weighs 19 Kg (41 lbs, 14 oz). The case is available either in silver finish or black, and all front panel controls are accessible via push buttons with red LEDs for function indicators. There is no remote control.

Front panel

From Left to right the controls are: Input –, input +, and mute. In the center, is a larger “standby” button. Next is the OS/NOS button which switches between the oversampling and the non-oversampling mode, followed by the phase invert selector and finally, the mode switch. Above the control is a line of red LEDs which, again from left to right, indicate which digital input is selected: Coaxial, AES/EBU input 1, AES/EBU input 2, Optical, I2S-1 (HDMI), I2S-2 (RJ45), I2S-3 (RJ45) and USB. Finally on the front panel are LEDs indicating whether oversampling was on or off, and whether phase invert was enabled or not and then the sample rate being processed. Two main sample rates are given for Linear PCM (LPCM) at 44.1 KHz and 48 KHz. Following those two numbers are the multipliers: X1, X2, X4 and X8. Following that is DSD which lights up when the T+ recognizes a Direct Stream Digital signal. The sampling rate LEDs show the sampling rate being decoded by lighting up either the 44.1 or the 48 KHz LED along with a multiplier. For instance, a standard 44.1 KHz data stream, as from a CD player will cause the 44.1 LED to light as well as the X1 LED. An 88.2 KHz sampling rate signal will light the 44.1 KHz LED and the X2 LED, etc.

Rear Panel

The rear panel of the T+ is, as is customary, for I/O. From left to right, are the audio output jacks. The first are the XLR balanced outputs (pin 2 = hot) and then the RCA unbalanced outputs. In the center, at the bottom of the apron, is the IEC mains connector which will take 115VAC, 60 Hz to 230VAC 50 Hz (no switching required. The unit senses the mains and adjusts itself automatically). At the top of the apron are the digital inputs. These consist of two BNC connectors which are the interface to a D-to-D converter if present (in our case, the Gaia) followed by an RCA jack for coaxial SPDIF input. Next is the Toslink connector for optical SPDIF, and then there are two balanced XLRs for AES/EBU 1 and 2. Next in line are the I2S inputs. I2S-A is an HDMI connector followed by two RJ45 connectors representing I2S-B and I2S-C inputs. Finally there is the standard type-B connector for the USB input.

Operation

The T+, like other Denafrips DACs, is pretty straightforward in operation. Connect your sources and select the one to which you wish to listen with the buttons on the front of the unit (regretfully, there is no remote control. This is something Denafrips needs to address in future models) and then choose whether you want oversampling turned on or not (OS/NOS). That’s about it.

While there is, at present, no industry standard for I2S pin-out, it is, according to many, the best digital interface on the market today. To facilitate this, Denafrips has designed the T+ (and others in their line) to adapt to most connection protocols in use today. While it is beyond the scope of this review, there is YouTube video available on the Denafrips website that shows how to use the buttons on the front panel to find the correct set-up for your I2S device. For instance, I use an HDMI connected, third party device to allow me to play SACD discs through the T+ using any Blu-Ray player that supports SACD playback. Once the correct interface is set on the Denafrips, all one need do is select I2S via HDMI as one’s input and insert an SACD into the drawer of a suitable player. Of course, there is no guarantee of the compatibility of any third party I2S device, but in my case, the SACD “adapter” was wired as the default configuration for the T+ I2S interface, so no configuration was necessary for me.

The T+ has two OXCO (Oven Controlled Crystal Oscillators) clocks operating at 45.1584 and 49.152 MHz. These two crystal clocks are encased in temperature controlled metal housings on the mother board and were designed to exhibit ultra-low phase noise and very high frequency stability (thus the temperature control) especially for digital audio applications. The oscillators are powered by a constant current power supply to ensure linearity and stability of the OXCO’s frequency and amplitude.

Jitter, a major concern for any Digital to Analog Converter, is handled in the T+ by re-clocking the incoming digital signal using a digital buffer device called a FIFO (First In, First Out). This device takes a digital “word” of any length supported, and momentarily stores it in the memory of the device. This means that the spacing of each incoming bit can be quite chaotic, and this would normally be disadvantageous to the performance of the analog conversion, affecting the resultant analog sound quality negatively. The FIFO circuitry won’t let the word out of the buffer until it is clocked out by the ultra accurate OCXO oscillator. Since the distance between each clock cycle is exactly the same from cycle to cycle with the OCXO clock, and each single bit is output for each clock cycle, the asymmetrical nature of the incoming signal is changed to a super symmetrical data stream in which jitter is reduced to just a few parts per million. In other words, to the extent of the accuracy of the clock; jitter is, for all intent and purposes, almost completely eliminated to the point that as a concern for the listener, it can be, essentially, ignored.

The T+ is equipped with a proprietary, state-of-the-art USB interface which supports up to a 24-bit/1536 KHz LPCM data stream as well as native decoding of DSD signals up to DSD1024. Available for Windows users is the Thesycon USB Driver (Mac and Linux platforms don’t need no stinkin’ drivers!). The USB circuitry is designed to only trigger when the USB input is selected. This feature is implemented to keep cross-interference between inputs at a minimum and to reduce possible digital noise pollution caused by the USB input which could degrade the audio signal-to-noise ratio.

In order to improve the performance of the SPDIF inputs (Coaxial, Optical (Toslink), and AES/EBU inputs) which operate up to 24-bit/192 KHz uses a proprietary on-board FPGA (Field Programmable Gate Array) to decode these signals rather than the customary Digital Audio Receiver chip. This shortens the SPDIF signal path, ostensibly allowing for less noise incursion and reducing coloration.

In addition, the T+ is equipped with a 26-bit R2R DAC to decode LPCM and 32-step FIR analogue filters in the hardware decoder to handle a DSD data stream. According to Denafrips, very few designs currently marketed where a R2R DAC can decode, using hardware, both LPCM and DSD data streams. It looks as if the decoding of DSD signals by the T+ is accomplished by converting the Direct Stream Digital signal to Linear PCM. I’ve read that while this approach works fairly well, the noise floor of the converted data stream is somewhat higher than it is for LPCM sources.

One thing that’s kind of unusual in the T+ is the output impedance of the balanced XLR outputs. It’s 1250Ω! That means that you want to avoid long runs of more than a meter or two to your amplifier. If you need long runs, it’s best to employ the unbalanced RCA outputs which are 625Ω, or employ a solid-state buffer stage between the T+ and the amp inputs. While 1250Ω seems high to me, balanced audio impedances can be anything as long as both the positive and negative terminals in a balanced circuit are the same.

The Gaia D-to-D Converter

This review evaluates both the Denafrips Terminator + DAC and the Denafrips Gaia Digital to Digital converter together as a system. While the T+ is, of itself, a breakthrough in DAC performance at its price point, this reviewer feels that the full potential of this DAC cannot be reached without pairing it to the Gaia D-to-D.

What Is A D-to-D Converter, Anyway

A D-to-D converter (DDC) is a piece of gear which takes a raw digital stream (in this case, audio) and removes noise from the transmission media, as well as from the AC line noise, then re-clocks the signal, reducing jitter, and generally hands-off the stream to the DAC as a much cleaner, purer digital signal.

Design Highlights

The Denafrips Gaia DDC accomplishes three main tasks: First, it isolates the incoming data from it’s downstream processes, using 50-Mbps photo-couplers or opto-isolators as they are known. This optical (as opposed to electronic) isolation of the incoming digital signals can lower the noise floor of the digital stream considerably, resulting in fewer errors and requiring less error correction during conversion. This can increase resolution by reducing interpolation (guessing) in the D to A phase and by improving the signal to noise ratio of the resultant audio output.

Secondly the Gaia buffers the signal and thirdly, it re-clocks the signal using a local OCXO. This may seem redundant as the T+ also has an on-board OCXO and it also re-clocks and buffers the incoming data stream, but the Gaia actually works together with the T+’s OCXO for synchronization. This means that not only do the two devices use the same clock frequencies, but the two clock’s square-waveforms start and stop at exactly the same time. This synchronization assures extra digital precision further “cleansing” the incoming digital stream with what I can only describe as remarkable results.

Gaia Front Panel

The Gaia has no power switch as it is “on” all the time. From, left to right, the front panel presents the user with three three rows of lights. Top to bottom, they read 44.1K, 64,  and 48K from left to right, the first row is marked 44.1K, 88.2k, 176.4K, 352.8K, 705.6 K, which obviously refer to multiples of the 44.1 KHz LPCM (Linear Pulse Code Modulation) sampling rate. Then there are lights signifying the following digital inputs: DSD, OPT, COAX. The second row is marked 64, 128, 256 and 512 for the Direct Stream Digital (DSD) formats supported. The bottom row is marked 48K, 96K, 192K, 384k, and 768K. These are, obviously, multiples of the base 48 KHz sampling rate. Following there are lights which indicate clock synchronization with the DAC and the remaining inputs AES/EBU and USB.

Finally, on the extreme left are a star or cross arrangement of five push buttons which are used to select the four inputs while the bottom-most button is the Setup button.

Gaia Rear Panel

From left to right are the Gaia digital outputs: AES/EBU1, AES/EBU2 (both XLR), I2S-A (HDMI), I2S-C (Ethernet RJ-45) Optical (Toslink) and Coax (RCA). Next are the Digital inputs: 49.152 MHz, 45.1584 MHz (BNC female – both from the same clock speed inputs on the DAC), Optical (Toslink) AES/EBU (XLR), and USB (USB “B” female connector) and finally, the EIA mains connector (115 V/60Hz or 220 V/50 Hz).

Setting Up the Gaia

To setup the Gaia for interface with a suitable DAC (in this case the T+) the user presses the Setup button once to enter the configuration mode. Then one presses the OPT button twice. After that, pressing the OPT button will toggle the clock light on or off to indicate whether the internal clock is being paired with the clock on the T+. I.E. Clock On = Enable Clock In, Clock Off = Disable Clock In. To confirm the setting, press the Setup button again to save the selected mode and exit the Configuration mode.

Connecting the Terminator Plus and the Gaia Clocks Together

To connect the clock OCXO’s of both machines together it is necessary to procure two 75Ω BNC male to BNC male cables of sufficient length to reach between the Gaia and the T+ (in this case). The two units should connect the same clock speed to the same clock speed; I.E, the T+’s clock inputs to the Gaia’s Clock inputs (see below).

Example showing the T+ and the Gaia’s clocks tied together

A Glimpse of Audio Nirvana

After living with the Pontus II for about a year, and then living with the original Topping D-90 DAC (with the original Asahi Kasei AK449 DAC chip, not the later D-90SE with the ESS SabreDAC) for several months, I decided to contact Denafrips about procuring their top-of-the-line DAC/D-to-D solution, the Terminator Plus/Gaia. As good as the Pontus II was, I found that the less than US$800 Topping D-90 bested it in a number of ways. First was, of course, price. The D-90 provided significantly superior SQ for less than half the price of the Pontus II. Secondly, the Topping supported full hardware decoding for MQA and Denafrips doesn’t support the protocol at all, and thirdly, the Topping has a full remote control, something no Denafrips solution offers, and which I consider almost de riguer.

The Topping blew me away. I couldn’t see how anything could be better than the Pontus II, but after hearing the D-90 in my system, I started to wonder if perhaps the T+/Gaia DAC combo might raise the bar on D-to-A conversion significantly further. I contacted Alvin at Denafrips in Singapore, and soon a T+ and a Gaia were on their way to me.

I expected the T+ setup to be better than the Topping and I already suspected that the hierarchy would be, in ascending order of SQ, the Pontus II, the Topping D-90, and the T+ setup. What I did not suspect was that the T+ setup would be the difference between viewing the road in front of one’s car through a muddy windshield, and viewing the road through one just cleaned with Windex inside and out! The only thing better, would be no windshield at all. We aren’t there yet (AFAIK).

To say that I was astonished, would be an understatement! After listening to the T+ alone for several days, I could hardly believe how much better it sounded than anything else to which I had ever listened! The Gaia can’t improve on this, I thought. So I hooked them together with a pair of 1 meter 75Ω BNC cables, and routed the digital output of the Gaia through the HDM I2S cable to the HDMI input of the T+. After connecting all my digital inputs to the Gaia: MacBook Pro to the USB port, Auralic Mini (for Tidal and locally stored files) to the coaxial SPDIF input, and my Logitech Squeezebox Touch (for Internet radio ONLY) to the Toslink input, I let the whole rig “cook” for about a week before sitting down to do any serious listening.

Oh My Gosh!

The T+ by itself had been a revelation, and I really wasn’t expecting much from the Gaia, I must admit.  I had tried the Gaia’s little brother, the Hermes with the Pontus II and had noticed very little if any improvement, so my expectations weren’t too high. Of course, the difference was that the Pontus II does not provide the clock interface between the DAC and the D-to-D like the T+/Gaia does; although the Hermes is capable of this with the right DAC (the only other DAC that Denafrips makes that can use the Hermes’ or the Gaia’s clock synchronization feature is the Terminator (without the plus). The Venus II, Pontus II and Aries II lines of DACs don’t support clock synchronization).

Well my first listen to the combo made me spill my adult beverage (and believe me, I’d as soon see a church fall down than spill my drink)! The T+ by itself was an eye-opener, but with the Gaia connected between my digital sources, and the T+, the sound quality is elevated to another plateau! I wouldn’t have expected that much of an improvement in SQ from a D-to-D converter. For many years I have had a Sonic Frontiers D2D converter box which re-clocked the incoming signal and up-converted 16/44.1 and 16/48 to 24/96, but the difference with, and without, the D2D box was subtle, at best. This improvement over the T+ alone is anything but subtle! All at once the soundstage opened up. It was already wider and deeper than any DAC I had ever tried, but it got even wider and deeper! To make sure that I wasn’t hallucinating (audiophiles are prone to confirmation bias. I.E., “I just got a new widget. It was expensive, and it’s highly touted. It must be better than the widget it’s replacing”, and so it is – in our imagination, at least!), I played one of my own symphony CDs. These were made from 15 ips (38 cm/sec), half-track analog master tapes that I recorded of the San Jose (CA) Symphony Orchestra under the world-class baton of the late Maestro Georg Cleve. I chose their performance of Ravel’s Daphnis et Chloe, the complete ballet. Here the orchestra is joined by the large Schola Cantorum choir of San Jose State University. The chorus was arrayed behind the orchestra on stage and stretched clear across the stage from one side to the other and in two rows. So from front to back, the ensemble consisted of viols and cellos on the front row, woodwinds on the second, brass behind the woodwinds on risers, and then the two rows of chorus on risers behind the brass. The recording was true stereo, as are all my recordings, made with a pair of Sony C-37P large-capsule condenser mikes in the cardioid pattern and mounted 7-inches and 90 degrees apart on a stereo T-bar. They were hung about 15 feet over, and slightly behind the conductor’s head. If anything could show the difference in soundstage between the Terminator Plus alone and the combination of the T+ and the Gaia, this recording, which images magnificently anyway, would surely be it.

Immediately, I was struck by how the entire ensemble opened-up in all three dimensions. The orchestra spread out to extend way beyond the edges of the speakers,  the ensemble also telescoped out, front to back, to take on the true depth of the stage in the venue where the performance was recorded! And suddenly, one could easily tell that the brass and chorus were on risers behind the woodwinds. The triangle shimmered over the left-side of the orchestra just as it does if you were sitting in the fifth row center in the audience. I’ve never heard this rendered so convincingly before from the CD, but I had heard it on playback from the master tape (which belonged to the orchestra, not to me). I had figured that digital simply couldn’t render that kind of detail. Indeed, I had only “glimpsed” this kind of image height from past DAC setups including the Topping D90 as well as the Denafrips Pontus II!

There is a new CD (December, 2020) of some never before released alternate takes of the famous Dave Brubeck album “Time Out”. This Album, on the Brubeck Editions label is entitled “Time Outtakes”. And also on the album are some never before released cuts that weren’t included in the original LP. Now I’ve had (and still have) several copies of the original release from 1959. I once had it on LP,  I have it on CD as well as on SACD (from Sony) and on Tidal as a streaming album. When I played the  outtakes I had a real hard time believing that the material on these two albums came from the same session in the same venue, recorded using the same equipment. The new release sounds so different; so modern, so palpably alive, that it really points out what modern recording practices and equipment can do, even with master tape material laid-down over 60 years ago! Having seen pictures of the recording  sessions for this famous album, I can tell you that they used Ampex 350 tape decks running Scotch 206  mastering tape. The electronics were all tube which were very noisy by comparison to today’s electronics, and Scotch 206 was likewise very noisy, even at 15 ips. However, the cuts on “Time Outtakes” sound like they were recorded yesterday using the latest in solid-state digital equipment! I really would recommend that you acquire this album. It is truly amazing sounding. If you have either Tidal or Qobuz, you can easily stream it, and if not, I encourage you to buy the CD or the vinyl release or listen on Amazon music Tidal or Qobuz. You can also hear this remarkable album by going to the “Brubeck Edition” Website (www.brubeckeditions.com) and follow the “Time Outtakes” thread to the page where you can listen to the album.

The opening few bars of “Take Five” on this alternate take features drummer Joe Morello playing the cymbal with his hard drumstick. With the T+/Gaia, one can hear the percussive tap of the stick on the cymbal and then the cymbal note as separate and distinct sounds! On most DACs this sound is smeared  to a greater or lesser extent, and frankly, I’m surprised that the primitive recording equipment of that era could even capture such microdynamics. Paul Desmond’s alto sax has a creamy, slightly “wet” texture that allows one to hear the breathy quality of a saxophone. Again, the separation of the player’s breath and the notes emanating from the sax’s bell is a real eye opener. I’m listening to this cut on my desktop system as I write this, and as good as the Schiit Modi Multi-Bit DAC is (for the price), none of these characteristics are even remotely revealed.

For Bass, I turned to the Saint-Saëns Symphony #3 in C minor, the “Organ Symphony” with the Kansas City Symphony Orchestra, Conducted by Michael Stern on Reference Recordings (RR-136).  The beginning of the fourth and final movement (Maestoso –Allegro) opens with this stupendous full C-major chord on the organ. If you wish to test your woofer/subwoofer, shake your house to the veritable foundations, this is the cut for you! Likewise, it is also the cut to test the bass authority of your DAC. With the T+ alone it is thunderous, but add the Gaia and it is not only a deep, tight organ note but it is also an extremely articulate one. The level of detail; the chuff of the pipes as air is pumped into them is distinct from the actual note that follows. When the note ends, it trails away in a very realistic and “analog” fashion. Something seldom heard on a digital recording.

Overall the T+ is a world class DAC. Alone, it produces a liveness and a palpable realism that just a few short years ago would have seemed impossible at any price. I don’t really know how to describe the refinement of that amazing performance made possible by the addition of the Gaia D-to-D. But all I can say is that whatever magic the T+ is bringing to the table with it’s incredible performance, the Gaia takes that magic and turns it into sorcery! The difference between the T+ without and then with the Gaia simply cannot be adequately described. I don’t know what the Gaia is actually doing at a musical level, but whatever it is, it’s beyond anything I, certainly, have heard before. I know that US$8,000 is a lot of money, but nothing else in my experience comes even close, and I’m talking about DACs that cost many times what the Denafrips Terminator Plus and Gaia combo will set one back. If there is better (or even as good) I’ve yet to hear it. OTOH, like I said at the beginning of this review, I believe that there is much more to be gleaned from our digital sources than current technology is able to extract from them. I’m sure that while the T+/Gaia stands at, or at least near, the pinnacle of what’s possible today, I’m sure that next year or the year after, they will be bettered, and perhaps at a more reasonable price. After all, the Topping D90 (again, not the Topping D90 SE) comes “close” to matching this pair, and does it for one-tenth the price. But at the moment, if you want a glimpse of what audio Nirvana is really like, The T+/Gaia is the price of admission.

Product Information:

• Denafrips Terminator Plus Digital to Analog Converter $6,451
• Denafrips Terminator Plus User Manual

• Denafrips Gaia Digital to Digital Converter $1,705
• Denafrips Gaia User Manual