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OK, so I got another gadget which is worth sharing with you guys :).

It’s a USB asynchronous DAC and amp called the Audinst HUD-mini. I wanted to be able to enjoy better music than my laptop (a 2009 Macbook Pro, so it’s not terrible in the audio department) can deliver. The main focus of this being that I have recently started listening to better encodings via iTunes with better headphones (proper music listening is relegated to my hifi, this is just for convenience so I needed portability).
The Audinst (I'd never heard of this company before) runs purely off the USB and when you plug it into the laptop, it shows up in the menubar as External SPIDF Interface (option click the loudspeaker icon in the menubar to get a list of possible outputs). This means the laptop isn’t using it’s own amp any more (so volume controls are greyed out and you have to use the volume knob on the external amp). No drivers to install, it just works. Better still, you can still use the equaliser in iTunes to modify the frequency curve (although, it sounds so good without that I turned it off - see below).
N.B. Remember to use “Audio Midi Setup” in Utilities to set the Audinst’s USB SPIDF signal to 96000Hz, 2ch-24bit when playing your 24/96 Tracks.



As you can see from the piccie above, it comes well packaged from South Korea and is marked as $10 so you won’t get stung by customs (check this with the vendor first).
I bought mine from an Amazon seller for the princely sum of £84 inc. delivery. Delivery took 3 weeks.



It uses a Burr-Brown 24bit/192kHz DAC with an output OpAmp that is socketed so you can switch out with other ones as you want. Having said that, the built in National Semiconductor LME49860 OpAmp sounds brilliant on it’s own, so I haven’t bothered rolling it.
It is also asynchronous with it’s own TCXO so it isn’t relying on your laptop’s clock output (it has it’s own which should theoretically give better sound quality).
It supports 44.1kHz, 48kHz, 88.2kHz, 96kHz at either 16/24bit resolution tracks.
The front LED is orange in standby and green when processing.



From the back you can see it also supports the ability to pass the DAC output to an external amp. This is switchable from the toggle on the front panel.
This is important, because the Audinst itself is on par with what the MBP can generate from it’s own headphone out...i.e. the amp in the MBP is only very slightly more powerful than the amp in the Audinst, so if you want to go louder, you’ll have to amp separately and use the Audinst as a DAC alone. Luckily, I had an old Musical Fidelity X-Cans (slightly modded) lying around so used that :D.


Sound: Right, on to the most important part of the review. My headphones have been my Sennheiser Momentum cans. To get more volume, for about a week I’ve been listening to the MBP through the headphone out (NOT lineout) and then into the X-Cans. This means the digital track is getting converted by the MBP’s DAC, amplified by the MBP, sent to the MF X-Cans and amplified again (whilst on it's way going through a 3.5mm to phono convertor and pair of couplers with 2 leads either end). The result? Louder but easy to hear sibilance and hiss and interference. Overall, quite poor and something I wouldn’t recommend.

I then used the Audinst alone. So (correct me if I'm wrong) the track is being fed directly/digitally via USB to the Audinst DAC which then converts it to analogue, amps it and sends it to your headphones - a much better signal path.

Result?  WOW! No hiss/sibilance, inky black background (with good recordings) plenty of bass and silky smooth midrange and treble. Yes, the Audinst doesn’t go quite as high as the MBP alone, but it sounds soooooooo much better because every instrument is clearer and more delineated than before. The soundstage is also widened but more importantly, instrument separation is spot on (similar to what my Westones can do). I found myself head-bobbing as my iTunes appears to have got it’s groove on again!

Overall I was extremely impressed. . .so much so that I almost immediately turned the iTunes equaliser off completely (option-command-2 in iTunes and uncheck the “on” box).


However, volume was loud but I wanted to see if a beefier amp would change things, so I used my Kelvin K2 interconnects to hook the Audinst up to my MF X-Cans and bypassed it’s own internal amp.



The result? Bass gets more meaty at the expense of a slightly more recessed midrange (which is so much more up-front-and-in-yer-face with the Audinst alone). It’s almost as if a teensy weency bit of the PRaT disappears when the X-Cans are plugged in but traded off for better bass. Oh, and the X-Cans go louder as well.

Regarding the Audinst in isolation, the sound quality is fantastic for such little outlay so I would give this a solid thumbs up and say that an external amp is purely optional.


In order of preference I would say:


  1. MBP -> Audinst                   OR                     MBP -> Audinst + external Amp                         (depending on your taste)
  2. MBP alone
  3. MBP headphone out feeding a lone external amp
  4. iPhone/iPod


Cost: This was only £84 and, as a standalone, it outperforms the built in DAC and Amp in the MBP so is definitely worth the money. The MF X-Cans cost me £60 second hand ages ago so an external amp can be fairly cheaply had to alter things as you’d like...but having said that, on it’s own the Audinst is no slouch so it has everything you need in one small box already...I'd definitely recommend it :cool:.