Schiit Asgard 2 Headphone Amplifier and Bifrost Uber DAC Review Highlights
The single ended class-A Asgard 2 is a solid state, all discrete headphone amplifier that can put out up to 1W of power into a 25 Ohm load. The 32 bit, 192 kHz Bifrost DAC also uses all discrete construction, and both offer great fit and finish, and build quality. For $668 total, it’s hard to believe these components are 100% made in the USA, but they are. Throughout my time with the Schiit components, they delivered iron-fisted control and exceptional recovery of detail with my Sennheiser HD600s. In addition to sounding far more expensive than they are, they also look and feel more expensive than they are. That’s a very hard combination to beat.
Schiit Asgard 2 Headphone Amplifier and Bifrost Uber DAC Highlight Summary
- The Asgard 2 is a single ended class A headphone amplifier with all discrete construction and no feedback in high gain mode.
- The Bifrost DAC is 32 bit, 192 kHz with all discrete construction and upgradable analog and USB input boards.
- Both components are entirely made in the USA from mostly US sourced parts, but still have a very low price of $668 for the pair of components as tested.
- The detail extracted by this pair of components is excellent, with sound quality far better than you’d expect for the price.
- The Asgard 2 has plenty of power to provide iron-fisted control over my Sennheiser HD 600s.
- Measured performance is excellent, even at over 5Vrms output level into 300 Ohms.
Introduction to the Schiit Asgard 2 Headphone Amplifier and Bifrost Uber DAC Review
Headphone amplifiers and associated components have seen an explosion in variety and quality in the past several years. Secrets has reviewed many headphone amplifier and DAC’s. The younger generation of music lovers has learned what some of us geezers have known for a while. Headphones are the least expensive way to gain access to truly world-class audio performance. In fact, headphones listened to by the young may just save our hobby from the mediocrity of earbuds and compressed audio formats. One of these new companies specializing in headphone electronics is Schiit Audio. Founded by Jason Stoddard and Mike Moffat (formerly of high end audio powerhouse companies Sumo and Theta, respectively), Schiit Audio is an irreverent company with a very serious mission: Schiit wants to bring fun back to our hobby by building very serious equipment at a relatively low price point. They have managed to deliver and have collected a large fan base on the intertubes. Like many lower price point companies, Schiit sells only manufacturer direct, but unlike many of their competitors, their products are entirely made in the USA out of mostly USA sourced components. I was very intrigued when I heard about this company and their business model. I asked for their most popular Class-A solid-state headphone amp, the Asgard 2, paired with their very well respected Bifrost DAC with “Uber” analog stage to test. Could this $668 component stack possibly compare to my venerable Headroom Ultra Desktop? Could Schiit possibly deliver components at the quality they claimed, made in the USA, for such a low cost? The short answers are yes and yes. I was surprised.
SCHIIT ASGARD 2 HEADPHONE AMPLIFIER AND BIFROST UBER DAC REVIEW SPECIFICATIONS
- Design: Headphone Amplifier, Solid State
- MFR: 20 Hz – 20 kHz, – 0.1 dB
- Maximum Power, 32 ohms: 1.0W RMS per channel
- Maximum Power, 50 ohms: 1.0W RMS per Channel
- Maximum Power, 300 ohms: 380 mW RMS per Channel
- Maximum Power, 600 ohms: 190mW RMS per Channel
- THD: Less than 0.008%, 20Hz-20KHz, at 1V RMS, High Gain Mode
- IMD: Less than 0.010%, CCIR at 1V RMS, High Gain Mode
- SNR: More than 102 dB, unweighted, Referenced to 1V RMS, in Low Gain Mode
- Crosstalk: Less than -72 dB, 20 Hz – 20 kHz
- Output Impedance: Less than 2 Ohms
- Gain: High = 6 (15.6 db); Low = 1.5 (3.5 db), via Rear Switch
- Topology: Fully Dscrete, Single-Ended Class A with Single Voltage Gain Stage; No Globall Feedback in High Gain Mode, 12 dB Feedback in Low Gain Mode
- Power Supply: Internal Power Transformer with 4 Separate Power Supply Rails and over 20,000 µf of Filter Capacitance
- Power Consumption: 30W
- Size: 2.25″ H x 6″ W x 9″ D
- Weight: 5 Pounds
- MSRP: $249 USD
- Design: Solid State DAC
- Inputs: Coaxial SPDIF, Optical SPDIF, USB (optional)
- Input Capability: up to 24/192 for All Inputs, Including 24/176.4
- Input Receiver, SPDIF: Crystal Semiconductor CS8416
- Input Receiver, USB: C-Media CM6631A
- D/A Conversion IC: AKM4399
- Analog Summing, Filtering: Fully Discrete, JFET-input Differential Topology
- Output: RCA Unbalanced
- Output Impedance: 75 Ohms
- MFR: 20 Hz – 20 kHz, ± 0.1 dB
- Maximum Output: 2.0V RMS
- THD: <0.002%, 20Hz-20KHz, at Max Output
- IMD: <0.002%, CCIR
- S/N: >110dB, Referenced to 2V RMS
- Power Supply: 5 Stages of Regulation, Including Separate Supplies for Critical Digital and Analog Sections
- Upgradability: Separate, Modular USB Input Card and DAC/Analog Card are Snap-in Replaceable
- Power Consumption: 12W
- Size: 2.25″ H x 6.75″ W x 9″ D
- Weight: 5 Pounds
- Price: $419 as Tested with Uber Analog Stage
- SECRETS Tags: Schiit Headphone Amplifier, Headphone Amplifiers, DACs, Headphone Amplifier Reviews 2014, DAC Reviews 2014, Bifrost DAC
Design of the Schiit Asgard 2 Headphone Amplifier and Bifrost Uber DAC
I was not expecting much in terms of fit and finish when I was opening the box I received from Schiit. What I took out of the box blew me away. No fancy packaging, but the components themselves were absolutely beautiful. Unlike many low cost components, both Schiit components had very custom looking, modern aluminum enclosures. The boxes were the same size and shared many key components, but were both of very solid, professional construction made of brushed anodized aluminum with perforated metal grilles. The inner box was a low cost stamped steel enclosure, but who cares? You can’t see that anyway. Internal parts and assembly quality was exceptional, almost impossibly exceptional for the price. Schiit doesn’t use ridiculously priced “audiophile” components. What they do use are top quality industrial components of the type I use when designing and building the radio astronomy electronics I build for my day job.
The Asgard 2 is a single-ended class A, all discrete FET amp with no feedback. If this sounds like the description of a $25k Pass Labs power amp, that’s because it is. Schiit uses a very similar discrete FET circuit topology as the great man himself uses in his megabuck products. But since the Asgard 2 is a headphone amp with a maximum power output of 1W, that can be done for a very reasonable cost. Inside the enclosure is a single high quality multilayer circuit board 2/3 filled with the power supply. A very beefy transformer and capacitor bank fills this space. This is a VERY serious power supply for a 1W amplifier.
The other 1/3 of the board has a single ended class-A all discrete amplifier circuit. In high gain mode, there’s no feedback. In low gain mode, a small amount of feedback (12 dB) is applied to reduce the voltage gain of the circuit. The circuit is simple, with a single JFET voltage gain stage and a MOSFET output stage. There’s a single ¼” headphone jack next to a nice machined aluminum volume knob connected to a very high quality Alps volume potentiometer. On the rear panel, there are two pairs of RCAs, one input and one preamp output, in addition to an IEC power socket, power switch and the gain mode switch.
The only really noticeable concession to cost are the little rubber stick on feet that come with the amp that you need to stick on yourself. It would be nice if there were screwed-on rubber feet. I’d pay another $10 for that. After plugging in a turning on the Asgard 2, something else becomes very apparent. The Asgard 2 gets HOT: so hot that there are warnings and notes throughout the owner’s manual. Don’t be alarmed. Class-A amps do this. It’s how they roll. The amp consumes 30W of power all the time, and pretty much all of that goes into heat. Because of this, the warm-up time for the amp is significant. I just left it running all the time. Unlike a big power amp, this little guy won’t heat up your room or burn a lot of electricity. I think this will also result in better long-term reliability. Temperature cycling is never good for any piece of electronics.
The Bifrost DAC is housed in an enclosure of the same design and size as the Asgard 2 amp, with changes only for rear panel connections, front panel controls and cooling vents. As with the Asgard, fit, finish and build quality are first rate and belie the low price of the DAC. The Bifrost is fully 32 bit, using the AKM4399 DAC chip with the ubiquitous Crystal Semiconductor CS8416 input receiver. If equipped with the optional USB input board, the asynchronous C-Media CM6631A serves as USB input. My Bifrost did not have this option, as I use an ASUS Xonar Essence STX audio card in my office computer to output a SPDIF stream to the DAC.
Unlike many DACs of this type, the Bifrost does not convert bit depth or perform any upsampling. It operates at exactly the bit depth and sample rate it is fed. For those of us who do computer audio, this is welcome as we can do all of our upsampling in software before the DAC ever sees it, and know exactly what the DAC will do to that signal. If you don’t have the option to upsample elsewhere, this bit-perfect signal handling may be a drawback. Allowing upsampling to be user selectable is certainly possible, but would add considerably to the expense, both in circuitry and in the necessary user panel buttons and displays so you’d know what the DAC is doing.
The Bifrost can accept inputs up to 24 bit 192 kHz with both the SPDIF and USB inputs, so you can upsample more or less to your heart’s content before the signal gets to the Bifrost. I did test the “Uber” analog stage, which replaces the standard analog output stage with fully discrete construction and no capacitors in the signal path. This $70 upgrade seemed well worth it. As with the Asgard, a significant portion of the internal volume is dedicated to the power supply, in this case, 1/3. The rest of the PCB houses the audio input circuitry, with header plugs for the two available daughterboards. The analog/DAC board is a separate piece, allowing future upgrades.
The USB board is also separate, allowing it to be ordered at the time of purchase, or added later for $150. It is also possible to upgrade the analog board at a later date from normal to “Uber” for $100. Like the Asgard, the rear panel is simple, with a Toslink optical digital and RCA coaxial digital SPDIF input, a USB input connector, a pair of RCA analog output connectors, a power toggle switch and a IEC jack for AC power.
Setup of the Schiit Asgard 2 Headphone Amplifier and Bifrost Uber DAC
I installed the Asgard 2/Bifrost stack on my desk at work, with the Bifrost on the bottom. The Asgard 2 gets so hot, you don’t want to block its vents or cook anything on top of it. Schiit provided a pair of their own high quality 6″ RCA cables to connect the two components. I just left both units powered on all the time so their class-A circuitry would come to a nice, steady equilibrium temperature. I used the Asgard 2 to drive my fairly new (but old in terms of years on the market) Sennheiser HD600s. The 300 Ohm HD600s are fairly easy to drive, but still benefit greatly from a high quality headphone amp. I broke in the amp and DAC by leaving music playing at moderate volume over the weekend. I am using JRiver’s Media Center 18, with bit depth padded to 24 bits, and sampling rate set to 176.4 kHz or 192 kHz depending on the source material. For most of the review, I engaged the software crossfeed circuit to emulate the Headroom processing I’m used to and enjoy.
The Schiit Asgard 2 Headphone Amplifier and Bifrost Uber DAC In Use
After break in, I began listening to the Schiit stack with my latest high res music download: Daft Punk’s “Random Access Memories” in 24 bit 88.2 kHz from HD Tracks. This is now my new favorite album, and I find myself listening to it over and over even through I have hundreds of GB of other uncompressed audio files at my fingertips. I immediately found that the Schiit components were able to deliver even greater resolution and detail extraction than my Headroom Ultra Desktop (now sadly out of production), and even better control and impact in the bass.
One prime example of this is the mini-history lesson in electronic music, “Giorgio by Moroder.” In this track, Giorgio Moroder is interviewed, with the autobiographical description of his life interspersed with the music. Daft Punk recorded this interview using various microphones whose ages matched the time period Giorgio was describing. Through the Schiit components, the Sennheiser HD600s were clearly able to distinguish the character of these microphones. Their character is so obvious, you’d think the voice was postprocessed to influence the timbre, but it’s actually all in the microphones used for the interview. The entire album is filled with Daft Punk’s very heavy synthesized basslines. With lesser electronics, these basslines can sound muddled and thick, but with the Asgard 2 and Bifrost they were supremely agile. There was never a hint of ponderous slowness, just slam, impact and speed. Transients both in the bass and in the midrange and treble were exceptionally fast and sharp.
On less synthetic music, the Schiit components continued to deliver. On Emiliana Torrini’s “Fisherman’s Woman”, Torrini’s voice was smooth and silky, but delivered an eerie presence unmatched in my experience. One of the reasons for this effect was the very up front, “close” soundstage of the Asgard 2 and Bifrost. By comparison, the Headroom Ultra Desktop put about 1/3 to ½ of the soundstage outside my head. The Schiit components put most of the soundstage in my head, with the vocals of Torrini right in the center of my head. This effect had both pluses and minuses. The up front presentation made the music very immediate and intense, but did reduce soundstage depth and space. There was no less soundstage positioning resolution, everything just sounded closer. Turning on and off or adjusting the software crossfeed had no effect on this close-in presentation. The crossfeed just made the imaging a bit more continuous from left to right.
Throughout my time with the Schiit components, they delivered iron-fisted control over the HD600s. While not particularly hard to drive, it’s clear they react differently to the electronics driving them. Many people talk about the Sennheiser veil. I don’t buy it. Sennheisers are laid back, but there’s no lack of detail, not in the slightest, when driven by proper electronics. With the Asgard 2 and Bifrost, they were sharp as a razor, even in the bass. Not the same skull imploding bass of the Denon AH-D7000s, but still plenty of impact and agility. Compared to the Headroom Ultra Desktop, I can clearly say I prefer the Schiit combo, even at less than ½ the asking price of the Headroom amp/DAC when you could still buy one new. The only thing about the Headroom I clearly prefer is the more spacious soundstage. If the Schiit components threw a larger soundstage, they would be perfect. Still, even with that one small drawback, I think they’re better and will very likely replace my trusty Headroom amp with the Schiit Asgard 2 and Bifrost.
The Schiit Asgard 2 Headphone Amplifier and Bifrost Uber DAC On The Bench
Measurements were performed with a M-Audio Profire 610 Firewire sound interface and Spectra Plus FFT analysis software. The Bifrost DAC was driven via the SPDIF coaxial input with a 24 bit 192 kHz signal. The Asgard 2 was driven with an analog signal from the Profire 610, but with the internal digital signal also generated as 24 bit at 192 kHz.
We’ll begin with the Asgard 2 amplifier. I used a 300 Ohm resistor as the load (actually a 560 Ohm and a 620 Ohm resistor in parallel for a ~294 Ohm load). Amplitude was set to about 5.25 Vrms, producing about 100 mW into the load. I measured total harmonic distortion plus noise with 60 Hz, 1 kHz and 10 kHz tones. The distortion levels were all very low, between 0.05% and 0.07%. Note, I tested at a much higher power level (more than 25 times higher) than used for the Schiit specifications. More important is the distortion spectrum. As you can see, most of the harmonic distortion is in the 2nd and 3rd harmonics, with much lower levels of distortion in higher order harmonics. This is thanks to the lack of feedback in the high gain mode of the Asgard 2. The human ear and brain are less bothered by low order harmonic distortion, so this is a very good result.
Intermodulation distortion was measured with a 60 Hz and 1 kHz tone. IMD is around 0.06%, similar to the THD numbers. This is also an excellent result, with the 60 Hz sidebands on the 1 kHz tone 70 dB down from the fundamental.
Frequency response is more or less board flat all the way to the maximum of the Profire 610. The roll-off near 96 kHz is the response of the soundcard, not the amplifier. The slight rise in response from low to high frequency is also the result of the measurement, not the Asgard 2.
A similar suite of measurements was performed for the Bifrost DAC. Distortion numbers are exceptionally low, and near the limit of the measurement setup, with values around 0.003% at 60 Hz and 1 kHz, rising to 0.007% at 10 kHz. The third order harmonic is highest, but higher order harmonics are within 10 dB. Regardless, the levels are so low as to be unimportant.
IMD is similarly low at 0.003%. Sidebands are over 90 dB down from the fundamental.
Frequency response is also pancake flat to the limit of the Profire 610. Again, the slight rise towards higher frequencies is an artifact of the measurement.
Conclusions about the Schiit Asgard 2 Headphone Amplifier and Bifrost Uber DAC
Today, you have a lot of choices when shopping for a headphone amp and associated DAC. If you ask the question: “Where can I get a solid state amp and DAC with world class performance, excellent build quality, made in the USA for less than $1000?” the number of choices drops precipitously. If components with the above description sound good to you, I strongly suggest you listen to the Schiit Asgard 2 and Bifrost. They are truly excellent sounding components. In addition to sounding far more expensive than they are, they also look and feel more expensive than they are. That’s a very hard combination to beat.