Metrum Acoustics Aurix

  1. zilch0md
    I agree - on both points. I will never sell my Aurix. (Well, maybe if I was starving.)

    That's a great deal, above - for people in the EU.

    491 Euro equals $561.83, currently.

    Cheap!
     
  2. zilch0md
    Well, if anyone was considering it, the factory direct price of the Aurix has been bumped up to 657 Euro.

    Meanwhile, I've had the Aurix in a lot of chains, but for several weeks now, I'm exceedingly happy with the synergy it has in this particular chain:

    Apple Touch 6 (an iPhone 6 without the phone) streaming Tidal HiFi to the DAC via Sonica App
    or
    88.2k and 96k FLAC files, read from 128 GB MicroSD cards, mounted in USB card readers at two USB ports on the Sonica DAC

    > Oppo Sonica DAC (ES9038Pro) (controlled by the Sonica App, but receiving Tidal HiFi directly from the WiFi router)

    > Audioquest Diamondback RCA interconnects (the best kept secret in the ludicrous AudioQuest RCA interconnect lineup)

    > Metrum Acoustics Aurix (set for 10 dB gain)

    >Toxic Cables Silver Poison cable

    > Beyerdynamic DT880 Pro 600-Ohm (with Beyer's pleather pads for better seal than velour)

    The typically difficult to read 6moons review of the Aurix suggests that it's a better match for high-impedance headphones than for low-impedance headphones like my Oppo PM-1 and Aureze LCD-2. I have to agree!

    I had purchased both Metrum Acoustics Octave MkII and the Aurix as a "fix" for the my cankerous Sennheiser HD 800, which is definitely happy with that DAC/Amp pairing, as the HD 800 is particularly sensitive to oversampling DACs (especially ESS DACs, it seems), but also to amps that use a lot of local or global negative feedback. The HD 800 sounds horrible on the amp section of my Oppo HA-1, a multi-stage design with a ton of feedback applied to eliminate the distortion created by the amp's own architecture - an amp that sounds absolutely wonderful with Planar headphones, especially when fed with 4x the power output of the 4-pin connector. But no matter which DAC is used to drive the HD 800 with the HA-1 amp section, the HD 800 can resolve and deliver to your waiting ears the very low-energy distortion artifacts that the HA-1 amp's application of negative feedback creates down near the noise floor - which really destroys all those micro-details that expand the soundstage and improve imaging. Just about any single-ended, zero-feedback (or, at least, very low feedback) amp (even the affordable and thus, unheralded - thanks to price bias - NuForce HA-200) sounds much, much better with the HD 800, as long as you've also eliminated the use of an oversampling DAC.

    Wow, I got on a soapbox there... But I was headed toward saying that if you think the passive (0 dB) or transformer-based gain (10 dB) Aurix lacks dynamic punch (as has been judged by some people), you are not giving the Aurix what it wants, in my opinion (and that of the frustratingly entertaining Srajan Ebaen) - and what the Aurix wants is a high impedance headphone, like the 600-Ohm version of the seemingly ancient yet still venerable Beyerdynamic DT880. Wow! I am so very happy with this chain - and the Beyer (which I've elsewhere described as "the poor man's HD 800," with slightly less resolution, a slightly coarser treble (not a bad thing - it's analogous to going from the too smooth Beyer T1 to the less smooth HD 800), but also with a far more appealing bass energy and extension") has none of the HD 800's sensitivity to ESS DACs, but to be fair, even when I use the Sonica DAC with the HD 800, it is much smoother in the treble, yet chock-a-block with the resolution that an HD 800 deserves. The only thing "finicky" about the Beyerdynamic DT880 600-Ohm is that it wants lots of power and the Aurix really finds its legs to deliver that power when pushing against a 600-Ohm load. This pairing has plenty of slam that's just not there with my planar magnetics and not even with the 300-Ohm HD 800. When you think "Aurix," think "600-Ohm load."

    In my chain above, to achieve extremely an extremely low noise floor, the Sonica DAC and Aurix are powered by a 500 VA Topaz 91095-32 isolation transformer (with an inter-winding capacitance of only 0.0005 pF, offering -146 dB of common-mode noise reduction and -65 dB of differential-mode noise reduction on the mains power). Both the DAC and the amp are plugged into the same outlet on the Topaz, for minimum impedance, and thus reduced vulnerability to audible noise from leakage currents that can evolve when a voltage potential develops between any two components. And... The WiFi router is powered by a 12V iFi iPower DC power adapter (with a shortened cord) that itself is plugged into a B&K 1604a isolation transformer (with floating secondary coil.)

    PS> My Metrum Acoustics Octave MkII is doing a great, NOS job of driving a $500, 24VDC battery-powered TBI Audio Millenia MG3 Class BD power amp (32Wpc rms into 8-Ohm, which John Hoffman, writing for Positive Feedback, describes as sounding very much like his $3000 Electra Print 300B, 8 Wpc, SET tube amp, believe it or not. I'm using the Octave MkII + TBI MG3 to drive a pair of Definitive Technology SM45 two-way bookshelf speakers, in a near-field monitor setup - at about arm's length from my head. I'm beyond sure they're not as good as something like the coaxial-driver KEF LS50s I'd love to try, but the SM45s fit my budget and have been highly praised by Chris Martens of Abso!ute Sound, who have often been accused of failing to review any affordable HiFi gear.

    I, for one, abso!utely love what the Metrum NOS DAC is doing for this near-field monitor setup with the SET-wanna-be Class BD, TBI MG3 amp. Here, again, I use a B&K 1604a isolation transformer to provide common-mode noise reduction on the mains power for the Octave MkII. I'm driving the DAC's Anamero-based USB card (with heavy design input by Cees Ruijtenberg), with data and power coming from an Uptone Audio USB Regen, that is itself powered by a 7.0V DC TeraDak LPS on another B&K 1604a isolation transformer. The USB signal is not coming from a laptop any longer. I've recently started feeding the USB Regen with data from, believe it or not, a Sony NWZ-A17 DAP, equipped with a custom USB emulation cable that bypasses the DAP's proprietary internal DAC to create an already very clean USB audio signal for the USB Regen. Alternatively, I will drive the USB Regen with an iPad 3, using a CCK. Clean, clean, clean - low noise floor and the monitors just disappear - very hard to place with my eyes closed, except when listening to tracks that have been mixed with signals going to only one channel.

    OK! I guess I felt like rambling this morning, but the big picture here is that I LOVE my Aurix with the 600-Ohm Beyer DT880!
     
  3. C17fxr
    Zilch0md, et all:
    Gentleman I want to start by saying Thank You all for a great read.
    I just purchased a used Metrum Menuet and liked what I heard so much I started researching what other products Metrum may have to offer.
    After reading about the Aurix, I was very intrigued by its implementation, after reading about it in 6moon's wasn't quit sure I would purchase it.
    Then I found this thread that changed my mind, I purchased the unit before I was able to read all the additional information provided here.
    Reading your thoughts along with your trial and errors made me realize this is almost like my heavely modified preamp which wound up being a passive buffered preamp by the time it was done.

    The unit should be arriving one day this week and I will keep you posted on the progress. The break in will be rather slow as I will be working overseas during the Holiday's, add to that, when I return home will be moving into a new home. I will get it broke in as soon as possible.

    Something that has crossed my mind that I want to try, is something similar to cartridge loading like I do with my vinyle rig except loading the headphone amp to work with my 32 ohm headphones.

    Anyway just want to thank you gentlemen for all the effort you have put into reviewing this amp.

    Keep the great information coming.
     
    zilch0md likes this.
  4. borrego
    The first thing you want to do upon receiving your Aurix is open up the cover, then press firm the two gain transformers into their sockets. The fitting of the two transformers always got loosen during shipping and it would affect sound quality.
     
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  5. richard51
    Just a question to the knowledgeable one: I have the AKG K 340 that i love, the Aurix would drive this difficult headphone without struggling to ?
     
    Last edited: Nov 7, 2017
  6. zilch0md
    With respect, I can't imagine why the AKG K 340 would be difficult to drive.

    Looking up the specs, it only presents a 16-Ohm load with a very high sensitivity of 122 dB. So... It should find enough power even with the likes of a Sony DAP (they typically produce only 10 or 15 mW peak per channel.

    I can't recommend the Aurix for use with the AKG K 340, because I've never heard it, but I will say that, in my opinion, the Aurix really sounds its best when used with high impedance loads, i.e. 300- or 600-Ohm. My prediction, just guessing, is that the Aurix would certainly have enough power to drive your ear buds, even when set to 0 dB gain, but I suspect it will lack the dynamics heard when the Aurix is used with 600-Ohm headphones, for example - especially if you are running the amp with the volume control at nearly maximum attenuation.
     
  7. borrego
    richard51 likes this.
  8. zilch0md
    ^ Wow! AKG is apparently "recycling" their model numbers:

    https://www.amazon.com/AKG-340-Canal-Bud-Headphone/dp/B0028N78A2

    https://www.headfonia.com/akg-k340-bass-heavy-version/

    I had no knowledge of the headphones preceding the ear buds with the same model number.

    @richard51 I can now see that it's likely you are talking about the headphones. The fact that they present a 400-Ohm load is a good thing for hearing the Aurix at its best, but reading the following paragraph from the Headphonia review I would guess that the Aurix might not be up to the task:

     
    Last edited: Nov 12, 2017
  9. richard51

    Thanks for your reply, yes i apologize for my imprecision. (what a bad idea to name 2 products with exactly the same name....:triportsad:)

    I have the Sansui AU 7700 that drive them from the headphone out very good i think but i was curious about the price/quality ratio of the Aurix....The Aurix seems interesting about all count in his category price....

    Thanks very much for the link....I will read it...
     
    Last edited: Nov 12, 2017
  10. C17fxr
    Just wanted to say I only have about 25 hours on my Aurix so far and love what I am hearing. Who knew there was so much space between your ears.
    My setup for this trial was rather simple as I am currently between homes, it consisted of a Dell XPS 17 laptop running Windows 10 and JRivers 23. This was connected to the Menuet with the supplied USB cord, the Menuet is connected to the Aurix with a Kimber KS-1026 interconnect and the Aurix powering Grado GS-1000i's.
    The set up impressed me so much that I went in search of a 600 ohm load to give this Aurix its due justice as recommended above.
    With that said I located a pair of Byerdynamic T1's (1st gen) that I was willing to purchase, unfortunately they will not arrive in enough time as I will be departing for an overseas rotation over the next several months.
    The good news is I should be in my new home by the time I return and with have my full setup available for auditioning and with it being the height of the winter months listening sessions shouldn't be hard to come by.

    Looking forward to seeing how this new setup will compare to my old and how well it will compare to my McCormack Platinum modded Integrated Headphone Drive (MPHD)

    If it sounds as good as I hope the MPHD will become an amp to drive a pair of desktop speakers.
    The thought of all this is going to make the next 70+ days just drag slower.
    Very excited about future finds and will keep you posted.
     

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