A good while back, I had reviewed the Halide DAC HD. I remember listening to it and thinking, “the tonality is really awesome, this is an hd capable dac that sounds warm as a NOS dac”. It was able to melt with Audio Technica AD2000 and I wished to find something else that could improve upon its main limitations, the lack of detail retrieval and its small soundstage. Something that could improve upon all the qualities of the Halide.

In a sense, the Metrum Octave Mk2 (which uses a completely different technology) gives me exactly that. The Octave is a NOS dac using 8 industrial chips in parallel and no output capacitor; the first revision was capable to play up to 176 kHz music (with mentions to rare exceptions able to reproduce 192 kHz music), with no oversampling. The general consensus of the Metrum Octave across internet has been that of a warm, smooth dac with very colourful tonality, sensitive to the transport used (I have read several suggestions towards Audiophilleo for example), albeit, for some, a bit too bloomy and lacking some treble resolution.

The Metrum Octave Mk2 takes part of the technology developed by Metrum for the Hex dac (16 chips in parallel), in order to add the same USB input module presented with the Hex, and to allow hi-resolution music reproductn up to 192 kHz from USB and SPDIF (just like with Hex). The USB module is a modified HiFace receiver, integrated within the Metrum Octave Mk2 board. Differently from the Hex, which didn’t draw power from the USB port, but just the signal, the Metrum Octave Mk2 takes both signal and power from the computer’s usb, and then adds an isolator inside the box. Compared to the first Metrum Octave version, where the dac and the board were separated, the Mk2 is a single box solution.

Gear used

For this test, I have used my Forza Audioworks twin usb cable, with and without the iFi Power to clean the usb signal upstream; I have used the Headamp AE-2 amplifier with Audio Technica AD2000, and a tweaked version of the Stax Srm-1 Mk2, with the srm-001 amplifier reworked and upgraded by head-fi member Audiocats.
I have used Di Marzio rca cables, which I consider transparent and low profile, and very neutral.
I always use Foobar2000 on Windows 8, set to bitperfect reproduction.
I have tried the Metrum also at a friend’s speaker system (without iFi), built like follows: Audiomeca Mephisto cd player, AudioNote 2.0 DAC, Opera Consonance Cyber 222 Mk2 preamp, Korsun V6i and BW CM9 speakers.

Sound Quality

Depending on the quality of the USB signal, the sound of the Metrum can be soft, bloomy, mainly focused around lower midrange. It’s sensitive to both transport and software. With Asio4all, it sounds more rounded and smoothered, while Wasapi makes it more linear and to my liking. In all cases, the sound could be described as lush, organic, and the music flows continuously without feeling hard or distracting. I have noticed that the sound is slightly drier when using Wasapi at 24 bit compared to 16 bit; in the latter case, there is a bit more bloom in the upper bass/lower midrange.

The sound character of the Metrum is consistent through all the gear I have used. I think the Metrum Octave Mk2 is the perfect source for the Audio Technica AD2000.
While Eximus DP1, by comparison, has a bump in the upper midrange, and makes the AD2000 sound too hot and screechy, the Metrum with the same headphones melts perfectly for an intense, present, detailed sound, with close to perfect timbre. The lushness, sense of wholeness, easy music flow come from the Metrum to maximize Audio Technica AD2000’s energy, presence and imaging capabilities. Both together contribute to a saturated tone.

Although the Metrum Octave makes the AD2000 shine with all its qualities, and completely hides the AD2000 defects (painful upper mids peak and a tiny bit of sibilance), critical listening exposes some limitations from the Metrum Octave Mk2. The lower range is ay bit tilted, especially against the upper midrange. Trying it with my friend’s speaker system, it sounds a bit subdued in the upper mids, while the AudioNote 2.0 tubes added some ‘magic’ to the same speaker, although blurrying some spatial details compared to the Metrum.
Compared to the April Eximus DP1 and modded Museatex Idat-44m, the Metrum Octave Mk2 (without the iFi power conditioner) lacks a bit of bass authority and sense of “SLAM”. The other limitation lays in treble, being a bit too subdued: albeit detailed, lifelike and present, the music at times feels like being unable to scratch the last veil before realism.
Compared to the Eximus dac, I think the Eximus is slightly more capable technically, and more detailed. Still, the Metrum Octave Mk2 has a more analogue and believable tonality.

When I introduced the iFi Power usb regenerator, I noticed an increase in crispness, capable to produce wider and deeper soundstage; the same treble increase added a sense of realism; the bass gained depth. Adding the iFi power regenerator on the Metrum is desirable upgrade, since it helps the DAC at the frequency extremes.
With the Metrum Octave Mk2 I want to listen to a bit louder volume than the Idat44-m, which also adds up to the increase in soundstag and dynamics, and sense of involvement.

Testing the Metrum Octave Mk2 with the Audiomeca transport and my Belkin digital cable in my friend’s speaker system, I didn’t hear any significant difference over using usb connection straight from my computer.

Conclusions

The Metrum Octave Mk2 is capable to offer much in a single package. Its affinity with Etymotic ER4, Audio Technica AD2000 and also babystax, confirms my idea that it would work with everything which won’t add too much thickness (like, instead, would have been Sennheiser HD650 headphones).
A particular point which strikes me (as I own such Audio Technica’s), is how good it sounds with the AD2000: such combo Metrum Octave Mk2 is one of the best possible combo for a a budget bit over 1500 Euro (thanks, also, to the low power requirements of the AD2000). Other good matching headphones could be Stax Lambda, or Koss ESP950.
Stax SR-007 and 009, with their virtually endless resolving capabilities, might enjoy sources with higher resolving power, albeit the Metrum Octave Mk2 didn’t leave me desiring anything when using the iFi Power and filtered outlet; also, Stax SR-007 would still need the benefits of an analogue sounding source like the Octave Mk2 behind it.

As a final observation, I was happy to see that a multithousand Euro transport (the Audiomeca) with a very highly regarded coaxial cable (the Belkin), didn’t bring any real improvements over the normal Usb connection, which speaks about the quality of such usb input, making the Metrum Octave Mk2 a very well thought stand alone solution, not requiring the purchase of additional usb/spdif converters to make its DAC section justice.