amp [REVIEW] Schiit Valhalla 2

SSL · March 24, 2017

Preface

While I had hoped to have this review out after about a week or so of solid listening, my plans did not account for what Valhalla 2 had in store for my ear holes. In short, Valhalla is the real deal, and much more so than I could have anticipated. Although I expected a tube amp to sound “different” from the solid state gear I was used to, experiencing well-implemented “tube sound” for the first time was a bit more than I was prepared for.

If it sounds like I’m hyping things up, it’s because I am. Let’s get to it.

Introduction

Valhalla 2 is a class A, all-triode, output transformerless headphone amplifier. This just means that it is a pure tube amp. It also omits a transformer at the output, which would normally serve to effect impedance-coupling with the load. Instead, the topology is DC coupled from input to output, and employs output capacitors.

As is typical of of such topologies, Valhalla puts out the majority of its available power when driving a high impedance load, and is capable of large voltage swing - 16 Vpp. This makes the amp a natural pairing with high impedance headphones.

What to expect from owning a tube amp

Tube amps are different from the solid state gear most are used to. First and foremost, the tubes in the Valhalla themselves run hot and require a few seconds of warmup before listening. That said, there is no need to wait for tens of minutes before listening to music; while the tubes do take 10-15 minutes to reach temperature, 30-60 seconds is plenty long enough before blasting angsty anime tunes.

The body of this particular amp becomes warm but never hot, as there are no components directly using the case as a heat-sink. In contrast, Asgard and Lyr both use the case as a direct heat-sink for the toasty class A mosfet output stage.

Tube amps are also inherently noisier and more distorted than solid state. However! This does not mean that tube amps are necessarily “tubey”; Valhalla has less than 0.2% distortion, as confirmed by real-world third party measurements. This well below the level where it would cause an amp to sound overly “lush” and not likely to have a significant impact on real sonic performance. The signature of the amp is in no way warm or rolled-off, either.

That said, be prepared for a little extra noise floor with a tube amp. There may also be a little audible, low-frequency hum coming through if the ambient noise floor is very quiet. None of this is an issue when actually listening to music. If it is, the amp is defective or the tubes need replacement.

Sound Impressions

I did most of my listening for this review using a variety of music (including minimally mic’d acoustic) over the following chain: Exact Audio Copy > FLAC > Foobar > WASAPI > USB > Bifrost 4490 > Valhalla 2 > HD 650. I also did a bit of listening with the Beyerdynamic DT 880 Pro to get some perspective from a brighter can.

A note on how I describe sound - I don’t like to go balls deep into elaborate descriptions of sonic qualities, like “fleshy” mid-range, “musical” tone, or “scintillating” oboes. At the end of the day, you just need to try this shit out for yourself if you want to know what it really sounds like to the last detail.

Dynamics / Impact / Slam

Valhalla does pretty well with dynamics; I feel like musical peaks are a bit less compressed compared to Magni 2 Uber, but it difficult to pick out the difference. Bass impact seems a touch reduced, however, at least with the stock tubes. Rolling in different tubes improves matters here; more on this below.

Clarity / Attack / Focus

In terms of clarity, I get the sense that there is a little bit of a haze to the sound. This could be tube microphonics, or just general tube noise. Either way, there’s no doubt that cheaper amps can sound more “clear” than Valhalla. That said, attack transients don’t suffer much from this lack of clarity; the “haze” isn’t enough to take the edge off or obscure detail.

Resolution / Contrast

Detail is always tricky to describe; outside of the very lowest of budget gear, it’s rare to hear things that “weren't there before” with a new setup. With that in mind, Valhalla is able to present the detail that IS there like I haven’t heard it before. Timbre and texture are very well defined and differences are distinct. Ambient sounds and spatial cues are also very apparent. Part of this is probably the slightly energetic treble; but something I’ve noticed as I’ve explored incrementally better amps is that I’m able to turn up the volume more with better amps before the sound becomes fatiguing. Low-end stuff tends to sound harsh and shouty when turned up, without providing additional detail to compensate.

Headstage / Imaging / Separation

This is the first thing that I noticed on listening to music through Valhalla and probably the best thing about it. It actually imparts width and depth unlike any amp I’ve heard so far. The presentation is airy and slightly diffuse, but still with precise imaging and separation. “Holographic” comes to mind as a descriptor, as sounds seem to emerge from and float in the air. This works particularly well with the HD 650, which has a relatively close stage for an open headphone. Orchestral music sounds properly expansive and there is less spatial compression during loud passages. Even better, highly compressed pop and other “wall ‘o sound” modern genres gain some welcome separation and layering.

If you’re wondering how an amp can change soundstage, I couldn’t tell you; it may have something to do with tube microphonics. What I do know is that this isn’t placebo. The difference in staging was literally jarring when the music first started playing through this amp.

Tonal Balance

Overall, Valhalla is pretty neutral, other than lacking a bit of oomph down low. There is a touch of treble grain at times with the stock tubes. Not enough to be fatiguing, but you notice it is there. This is a minor issue, and it is resolved easily by rolling in a better tube. The stock tubes also feel just a touch light in the bass, which might also be described as soft or lean. As mentioned previously, a simple tube roll alleviates this. Mids are nice and full, which gives nice tone to the instruments that hang out in this range.

Tube Comparison

Valhalla 2 takes four tubes, two input/preamp/driver tubes, and two output/power tubes. There is not much point in rolling the output tubes as there are few options and what options there are make little sonic difference by my research. The input tubes offer more options and based on reports of good results with the 6CG7 tube family, I chose a pair of tubes made by Electro Harmonix. I purchased the tubes from tubedpot.com: https://www.tubedepot.com/products/electro-harmonix-6cg7-eh-gold-pin-preamp-vacuum-tube

Stock 6N1P Tubes

Slightly lean or more likely lacking in impact
Airy, diffuse presentation and 3D headstage
Good imaging and separation
Very resolving, textured
Slightly hazy
Slightly grainy or rough treble

Electro Harmonix 6CG7 Gold-Pin

More bass slam and a touch tighter bass
Staging might be more centered between the ears
Smoother treble, but still energetic
Slightly laid-back upper-mids and maybe lower-mids
Details are retained
Instrument timbre seems slightly inferior due to a touch more coloration, but the overall balance is better

Summary

Strengths

Headstage, imaging, sense of space
Mid-range tone; outstanding for male and female vocals, low strings, piano
Resolution, texture, and dynamic contrast

Weaknesses

Slight lack of clarity; hazy
Rough or grainy treble at times, particularly stock
Lack of ultimate slam, speed, and impact

I think I can best quantify the upgrade in performance with this amp with a direct comparison to the Magni 2 Uber. If the Magni provides 5% of improvement overall, Valhalla 2 is on the order of 30%, if not more. The benefit of Bifrost is also multiplied through this amp, which compounds the benefit that each component brings individually to the system.

Bottom line, Valhalla is by far the first amp I’ve tried that made a significant, positive difference in sound quality. Magni 2 Uber is boring in comparison, and stuff like Fiio doesn’t bear mentioning.

Conclusion

Sounds damn good.
Good value. If people are spending $1k and up for headphones with arguably less sonic merit, this amp is a no-brainer at $350.
Reveals the capabilities of the Bifrost 4490 and the value that a better DAC brings to the table.
EXCELLENT synergy with Sennheiser HD 650. Enhances the warm mid-range while extracting detail and increasing headstage.
Brings out the best of the Beyerdynamic DT 880, but does no favors to the elevated treble; would probably kick ass with the new Amiron Home, though.
HIGHLY RECOMMENDED to owners of high impedance headphones such as Sennheiser HD 600/650 and many Beyerdynamics.