Emotion. Body. Presence. Realism. The Donald North Audio Stratus 2A3 single ended triode tube amplifier is Donald North's foray into Summit-Fi and follows on the heels of the popular DNA Sonett (now in its second generation). The Donald North signature blue powder-coated finish and fantastic build quality makes a true statement and is part of the experience of owning a real piece of audio art.
Designed to operate with both low and high impedance headphones, the Stratus has a completely silent background and is a purist class A single ended triode (SET) design. To provide the user with a wide range of configuration options, the Stratus' single-ended headphone output has user selectable output impedance between 8-ohm and 120-ohm, and selectable gain attenuation between 0dB and -6dB for greater volume range.
The XLR outputs have 8-ohm output impedance and come in both dual-3-pin and single-4-pin variety. The 4-pin XLR output is labeled K1000, the legendary headphone which provided inspiration for Donald to develop the Stratus. And with 1.8W (into 50 ohms) of output power, I can confirm that the Stratus has enough juice to power the AKG K1000 (and the even harder to drive HiFiMAN HE-6). But the real standout pairing with the Stratus is the Sennheiser HD800. The Stratus-HD800 is one of those magical combinations where you can simply forget that you're listening to music being reproduced, and instead just listen to, and become one with, the music.
The stock tube complement of the DNA Stratus includes a Winged "C" (SED) 5U4G rectifier, a Sovtek 6N1P dual triode input/driver tube, and 2 Shuguang 2A3B directly heated power tubes. Donald has done a great job here finding budget tubes that provide rock solid performance, musicality and lush intimacy.
For enhanced resolution, speed and increased soundstage layering, popular tube upgrades for the Stratus include: EML Meshplates, Sophia Princess, and Shuguang Nature Sounds for 2A3's; EML 5U4G Mesh, NOS RCA 5U4G, and Ken-Rad CKR 5U4Gfor the 5U4G rectifier; and NOS 6BQ7A's and Cryoset 6N1P's for the input tube.
Originally released in 2012, the Stratus has undergone one revision change in 2013 with the introduction of new balanced choke-filtered 2A3 filament supplies. This upgrade option was offered to all Stratus owners at the time and is included in all current production Stratus amplifiers. The main result of this upgrade was an even blacker background, enhanced soundstage layering, and an increased sense of three-dimensional realism.
The DNA Stratus is an incredible value at $2700. It is worth noting that lead times for the Stratus can be fairly long due to the nature of it being a custom-built product. But good things come to those who wait, and the Stratus is certainly worth waiting for--especially if you're an HD800 owner looking for an end-game rig.
At less than $300 for the pair of them, each essentially built for the other--and performing as well as they do as a system--I couldn't bring myself to separate the Schiit Modi 2 Uber and Magni 2 Uber for this guide.
The Modi 2 Uber has asynchronous USB 2.0, Toslink SPDIF, and coaxial SPDIF inputs, and can support up to 24/192 via all of those inputs. The DAC chip inside is the AKM4396. It has single-ended analog output via a pair of RCA jacks. My first-gen Modi (and the current Modi 2 non-Uber) support up to 24/96, and have only USB input.
As a DAC that has had tremendous attention paid to its measured performance as well as its sound, the Modi 2 Uber reads like a DAC that couldn't possibly be priced at $149.
The Magni 2 Uber might be even more ridiculous (and I mean that entirely as a compliment). For 149 bucks, one expects a simple opamp-based design (not that there's necessarily anything wrong with such amps), but the Magni 2 Uber's topology is described by Schiit thusly: "Fully discrete FET/bipolar, constant feedback through audio band, complementary VAS drive, Class AB, DC coupled throughout." I can't think of another fully discrete amp at its price point, other than Schiit's own Magni 2 (non-Uber version), which I haven't yet heard, and that goes for even less at $99!
The Magni 2 Uber has single-ended input via a pair of RCA jacks, and also has a preamp output that's controlled by the volume pot, and switched via the headphone jack. I intend to eventually use these preamp outs to feed active studio monitors (loudspeakers). My original Magni (and the newer Magni 2 non-Uber) do not have the preamp outs.
What does the Magni 2 Uber drive? So far, everything I've thrown at it. Rated at a maximum 1.5W into 32 ohms--and with a very low noise floor--I've driven several headphones, from my most sensitive IEMs to some harder-to-drive planars. With my most sensitive in-ears, I get a rather loud pop during both plug insertion and extraction, but, once in, the Magni 2 Uber is dead silent, even with my FitEar MH334 custom, which seems to be able to touch just about any amp's noise floor.
The Magni 2 Uber's versatility is helped by two gain settings, switchable via a rear-mounted switch. Also, its output impedance is only <0.2Ω, so that's a non-issue.
I've only used the Modi 2 Uber and Magni 2 Uber together as a stack, so I haven't yet compared each separately to other DACs and amps, but I can say emphatically that together they're a DAC/amp combo that represents the best DAC/amp combo I've heard for anywhere near $298, which is just an insanely low price for how great this stack of Schiit sounds.
Compared to the first-generation Modi/Magni stack I have, the Modi 2 Uber / Magni 2 Uber combo is richer sounding--the first-gen stack kept me plenty happy, but, in direct comparison, sounds less authoritative and more clinical to me. Using the ultra-transparent HiFiMAN HE1000 to compare them, the newer "2 Uber" stack provides more resolution and refinement, and, again, richer tone. If you spent almost all you had on the $3000 HE1000, and had only $300 left to spend on the rest of your system, here it is.
For five years, Schiit Audio has been one of the coolest stories in our community, and the Modi 2 Uber and Magni 2 Uber will only strengthen our enthusiasm for this company that was founded by a couple of wily audio industry veterans. Since Schiit's launch, it's been hit after hit from them--including (on the other end of the price scale) the best sounding DAC we've yet heard at Head-Fi HQ (the Yggdrasil)--and the tiny Modi 2 Uber and Magni 2 Uber may be their biggest crowd-pleasers yet, for their performance far beyond their price.
One of the best tube amps I've heard, in a variety of rigs, is the Woo Audio WA 5 LE, a two-chassis, single-ended triode, transformer-coupled, Class-A headphone amp that uses the venerable 300B tube. I personally love the sound of a great 300B amp, and the WA 5 LE is a great 300B amp. Though I don't have one yet, that may have to change. As is customary with Woo, the WA 5 LE uses point-to-point wiring.
Whenever I think of the number 11 in audio, the famous “turn it up to 11” scene from Spinal Tap comes to mind. While I don’t think that that was what Kingwa (He Quingua, the owner of Audio-gd) was thinking when he named the amp, the first balanced amp I had from him, the Phoenix had a volume control that went up to 99. It may well have been the first commercial headphone amp to use relays and resistors to control the volume via a rotary encoder and digital controller. The NFB-1AMP reminds me a lot of the Phoenix, given that it is in the same size box as the Phoenix was, albeit a one-box solution compared to the older amp’s two-box system in the manner of a Mark Levinson design.
While little seems to have changed over the years, Audio-gd amps spotting multiple inputs, pre-amp output, digitally-controlled resistor-and-relay volume control and Audio-gd’s own take on a current-gain amplifier, incremental improvements have kept Audio-gd’s products competitive. Not needing to spend vast amounts on marketing, promotions and fancy cases make their products quite a bargain. What is more, I’ve discussed with Kingwa the efforts he makes to find good workers and subsequently take good care of them as individuals, both for their sake as well as to ensure the quality of the final product.
Feature-wise, the NFB1AMP packs no less than 5 inputs: 2x XLR balanced inputs, 2x RCA single-ended and 1 set of ACSS current system inputs, which are intended to be attached to one of Audio-gd’s DACs. Outputs are either the balanced or single-ended headphone outputs or balanced or singled-ended pre-amp outputs. Audio-gd’s balanced products are ideally intended to be used at least with the balanced outputs, especially with headphones, as the single-ended outputs wont utilise half the electronics. Instead Audio-gd usually provides single-ended versions of their products designed for people who don’t have headphones with a balanced cable and don’t want to re-terminate theirs.
If you have a pair of headphones already with a balanced cable, such as from Audeze or MrSpeakers, or a pair of active monitors, then once you’ve got a DAC, you’re all set with a great desk rig. Audio-gd’s matching DACs, along with their amps, share the ACSS connection system, intended for higher-quality signal amplification and transmission. Externally it connects the current-gain circuits between components, bypassing the conversion to and from voltage transmission and negating any concern about what interconnects to buy as the cables can be ordered from Audio-gd.
The Audio-gd house sound is one where the amp simply disappears and it was that way with the NFB-1AMP. People talk of amps with a black background, but the non-feedback designs from Audio-gd I’ve only experienced a similar feeling with from amps from Bakoon Japan (which use similar technology) in producing a that seems to be both very smooth and very detailed without being rolled off at all. It is more as if the music has just appeared, suddenly, out of a black hole of nothing, with a complete lack of distortion.
That makes brighter headphones, including ones with a livelier treble, wonderful to listen with. The HD800s simply sound fantastic, as do the MrSpeakers Ethers. Warmer-sounding headphones aren’t left behind at all, with as much pleasure to be gained from Sony’s MDR-7Z and Audeze’s LCD-X, and there is enough volume range in low-gain mode that IEMs, if not excessively sensitive, will work from the single-ended output.
The NFB-1AMP doesn’t quite match my ALO Audio Studio Six for ultimate dynamics, but the degree to which it is close using a Chord Hugo as a source means that I will have to upgrade to Schiit Audio’s Yggdrasil for a more fair comparison I think! To get better from Audio-gd, one would have to buy the much larger, much hotter-running and more expensive Master 9 amp.
If you’re after a moderately-sized and effortlessly powerful headphone amp and pre-amp that just gets out of the way of the music, put the NFB-1AMP on your shortlist.
Going back to 2013-2014, there was a particular brand gaining a whole lot of attention in the audio world. With beautiful design aesthetic, robust build quality, and sonics to match, AURALiC quickly distinguished itself by offering high end audio products at attainable price points. Founded in 2008 by Xuanqian Wang and Yuan Wang, AURALiC committed themselves to creating a series of user-friendly audio products combining the most modern audio technologies, while focusing on advanced design aesthetic. Which brings us to the AURALiC Vega DAC, and Taurus MKII headphone amplifier. These two highly regarded audio products have gained an incredibly strong following and when Summer Yin, AURALiC North America’s Sales Manager contacted me to ask if I wanted to demo these units, I was happy to oblige. It’s always fun to listen to audio products that you have read so much about and even more fun when your expectations are met and even exceeded.
The Vega and Taurus MKII are both housed in matching, 2/3 size chassis with beautiful machined and sculpted alloy faceplates and in the case of the Vega, a gorgeous 512x64 OLED display. Both units use soft red indicator LED’s, and wonderfully damped spherical volume knobs. The units themselves are 11”W x 9”D x 2.6”H with the Vega weighing in at 7.5 lbs. and the Taurus at 8 lbs. The units come with a full host of inputs and outputs enabling a fully balanced configuration.
I used the Vega and Taurus MKII in a variety of configurations mostly fed by an Aurender N100H and switching out between the Utopia, HE-6, and HD800. The Vega DAC is not only a highly advanced DSD/DXD DAC, it’s also a high quality preamplifier capable of balanced output. The Vega’s volume levels are controlled by a 100 step digital controller which does not compress dynamic range and comes with a remote control that enables the basic functions of switching inputs, controlling volume, as well as some of the not so basic ones like dimming the OLED panel display. One of the Vega’s signature features is its Femto Master Clock which yields extremely low jitter measurements and includes three master clock control settings: AUTO, FINE, and EXACT. The unit also provides the user with selectable digital audio filter modes for both PCM and DSD formats. I found myself mostly switching between Filter Mode 1 and 4 but found it nice to be able to tailor a specific filter mode based on the type of music and quality of recording I was listing to.
The Taurus MKII is a fully balanced solid-state headphone amplifier and preamplifier that provides selectable single-ended and balanced inputs and outputs. The amplifier has a set of proprietary ORFEO Class A output modules which according to AURALiC achieve extremely low distortion performance. The modules themselves are said to be inspired by the Neve 8078 analog console’s circuit design with the goal of achieving a similarly type of warmth and natural sound signature. With it’s generous power ratings of 4,500mW into 32 ohm loads (single-ended) or 120 ohm loads (balanced), the Taurus is capable of handling any headphone, including the hard-to-drive HE-6.
The sound quality of the AURALiC Vega DAC and Taurus MKII amp is in a word, stunning. It’s a lofty goal to achieve a captivating sense of musicality while retaining the technicalities that audiophiles value. Too often, resolution is achieved at the expense of musicality and with this combo, AURALiC have managed to bridge the gap and let us have both. In terms of specific pairings, I found myself mostly listing with the aforementioned HE-6 as the Taurus MKII amplifier is one of the very few headphone amps that I have heard that can make the HE-6 truly sing.
The AURALiC Vega retails for $3499 and the Taurus MKII retails for $1899. Starting on November 18, and until supplies last, AURALiC will be offering the units at a promotional price of $2500 for the Vega and $1329 for the Taurus MKII. If you are in the market for a high end DAC and/or headphone amplifier, you owe it to yourself to try and audition the AURALiC products. Highly recommended!
For a long time there has been a fascination with cheap tube amps on Head-Fi. For many years Little Dot and Darkvoice had the lead. With Schiit storming in with their inexpensive Asgard and Valhalla, their cheapest all-rounder hybrid was the Lyr.
Their first attempt at a very inexpensive tube amp, the Vali used sub-minature tubes. Intended for hearing aids before the advent of the transistor, they are capable of producing good sound, but can be pretty noisy, and in Schiit Audio's inexpensive aluminium cases would ring like crazy if the case was tapped. They also had a high failure rate (at the factory) making the amp a pain for the company.
With the Vali 2, Jason Stoddard gave up trying to keep the tube in the case and relented to having it stick out of the top, negating the need for tricky thermal management. He has also selected a tube for which there are a number of types which can be used its place. After solving the issue of the multiple voltages required for the circuit via the use of a dual-voltage transformer inside the wall-wart, Schiit Audio managed to keep the price down to a crazy low $169 by keeping everything simple, from the basic chassis to using the simplest parts.
After a day of being left powered on, the Vali 2 will show some serious potential, punching way above its price point. With more delicate and calm music it is a joy to listen with, throwing a good soundstage with either the relatively easy to drive MrSpeakers Ether or the Sennheiser HD800.
While demanding music can show some strain in the performance, such as horns in classical and jazz music became a bit shouty and harsh, and complex music can sound blurred compared the more effortless presentation of more expensive amps amps, the bass punch is impressive even with high-end headphones, even the HiFiMan HE1000 and MrSpeakers Ether Flow. However this is only when I compared the performance to much more expensive amps.
I sure as heck don't feel like I am listening with a $169 amp, more like one that was at least triple the price, and I'd readily forget which amp I'd plugged my headphones into while it sat on my desk. Not only that, but a fair bit more detail retrieval than I had expected. For example, the slight flatness in the sound of the remaster of Jack Johnson's Bushfire Fairytales album was just as apparent through the Vali 2 as it was through my more expensive amps. That degree of looseness and blur to the sound was still there, but knowing that I'd have to spend 4-6x the Vali's price to better that I have been very impressed.
Since the Vali's output impedance in low gain mode is a usefully low 1.2 Ohms, it can do quite a reasonable job with IEMs. With the 12-driver JHAudio Roxannes, I was rewarded with a pretty good and clear result, along with some quite thumping, if slightly out-of-control bass, with only a bit of sibilance in the treble on Morphine's Buena while the Yggdrasil's lovely mid-range vocal reproduction was kept sufficiently pure. Quite a good result, even if the Vali 2 is not the amp I'd choose as a first preference for IEMs, as the various DAPs and amps I have on hand are better controlled and more precise-sounding. However, the Vali wins for entertainment value, if the DAPs do a better job when it comes to purity of sound.
What is more, as Schiit Audio are limited to including tubes that they can buy inexpensively in bulk, finding a good tube on eBay will almost always be an upgrade, so much so there is an entire thread on tube-rolling for it. The Vali 2 has enough power even for the 6SN7, so with tube adaptors and socket savers, quite a variety will work in the amp, giving it an distinct sonic upgraded.
What is most amazing is how the Vali manages to keep one entertained yet keep it together at the same time, compromisingly only a little at either end of the spectrum, and yet only costs $169 and still under $200 with the addition of a good tube. Put it together with a Chord Mojo or a DAP of choice and a nice tube off eBay and you have a rig under $1000 that will power even high-end headphones entertainingly well.
This amp is a big deal because it's the first true flagship electrostatic headphone amplifier from STAX in over 20 years, the previous one being the venerable Stax SRM-T2 in 1994.
The new flagship STAX SRM-T8000 is a hybrid tube/solid state electrostatic headphone amplifier that is fully balanced, and uses 6922 dual-triode tubes for the first stage, and a solid state Class-A output stage. Stax's goal for this amp was ultra-low-noise, and accurate, rich musical expression. Our time with the SRM-T8000 strongly pointed to that goal being faithfully realized. It's a spectacular amp, and a substantial improvement over the STAX SRM-007t and SRM-727 amplifiers.
We posted a Head-Fi TV episode about the flagship STAX SRM-T8000, so make sure to watch it below.
You know, I’ve never owned any Schi….um, any of your products..” I was saying to Jason Stoddard in LA in March. Indeed, the last time I’d sampled anything from his company was years ago at a meet in Australia, where an original Asgard hadn’t impressed me. So I asked Jason if he would send me a Valhalla 2 once they were in production, as the amp seemed to be something of a potential all-rounder, unusual for an OTL tube amp, which would normally be suited only to high-impedance headphones of 300 Ohms and above.
The Valhalla 2 blurb says that you can use it even with planar headphones and IEMs, even if the power output at 50 Ohms was going to be a lacklustre 180mW. It did indeed seem to deliver music, at least basically to a pair of LCD-X but some strain in the sound suggested that it wasn’t a good pairing and switching back to my Studio Six was a huge sonic relief. My 300 Ohm HD-800s paired vastly better with the soundstage nice and wide, if the clarity and instrument delineation was behind that of the more expensive amp. More noticeable out of the box was that the sound wasn’t “tubey” at all, but had a bit of bite — a bit of harshness on the leading edge of notes.
I hadn’t hooked up the Valhalla 2 up to anything special power-wise (it was plugged into the same power strip as my computer) and I was using a Geek Out as a DAC, but what was surprising was how much difference it made going overkill and using my Chord Hugo as a source, both with headphones and speakers, demonstrating just how good the Valhalla 2 is as an amp. While it doesn’t at all compete with the amp-is-not-there effect of my Studio Six, it is vastly better value at less than 1/10th of the price.
With a pair of high-impedance headphones from Sennheiser or Beyerdynamic, a DAC of one’s choice and a pair of active monitors from the likes of Emotiva, Adam or others would make the Schiit Valhalla 2 a great centrepiece for a great all-round desk rig. At $349 it is a screaming bargain of an amp.