Mike Piskor 2015

The Micro Portable Amp By Portaphile

Sound Impressions

For those unaware or unfamiliar with my history of reviewing portable amps, I tend to be super critical of the experience.  I cannot find much wrong with the Portaphile Micro at this price point and most if not all of my findings that were negative were all subjective opinions that had nothing to do with the quality of the product, but rather what I prefer my experience to include.


The Micro offers a bit of a neutral experience: Neutral ground, not neutral tone, meaning it plays well with headphones and sources of various types.  For example, you don’t want to combine a forward headphone with a very relaxed amplifier or vice versa.  Anything that offers something that isn’t neutral in setup is something that is specialized and doesn’t offer a high value in user friendliness.

The Micro is on the low end of forward in physical locale, something I would classify as just one step into the world of forwardness and engaging, but also something that is right on that boarder-edge of middle ground.  This means depending on the rig, you will get a slightly relaxed sound, or a solid-forward sound.  The sum of the experience is less dependent on the Micro, and more dependent on the pairing of the headphone and source with this amplifier.  With that gentle forwardness in mind, the experience sounds just a bit enveloping without sounding overly in your face.  As a result of that, the stereo imaging from left to right is not as vividly obvious as some other amplifiers in the $499 and up crowd.  Forward sounding gear makes it a bit harder to define the edges of the sound stage, so I would recommend you pair this headphone with intimate sets that do not have a focus on stage width.

Height and depth of field are very good for the price, all be it not the best….but a close second for this type of an amplifier.  Compared to my F-35 Lightning from Ray Samuels, the Micro is a step behind in depth of field, but it retains a more aired out sense of width.  The instruments, especially in treble instances, carries less solidity, but also more airiness.   In turn, that makes it sound a fair bit wider.  But, wider doesn’t mean better per say, as the F-35 ( $499 as well ) offers a more realistic appeal, sounds emitted simply feel more weighted and focused, as well as a bit more clean and clear than the Micro.  No question that the Micro trumps my F-35 and my SR71B in instrument separation.  That stage feels like there is more air between subjects in the track than Ray’s amps.


The low end of the amplifier, as paired with the likes of my bass titan: the Fostex TH600 with Lawton specialized wooden cups, ended up feeling less defined than with the RSA amps as well, but still not that far behind.  What I’d noticed is that the general brightness of the Micro is more than a few clicks above the very dark sound of the Ray Samuels house sound.  As a result of that, the Bass feels like it isn’t as vivid in the fray of a complex track.  This isn’t a fault of the amp, just that dark sound usually makes everything pop more.  In this case, the Micro feels like it is in need of a darker background effect, something akin to the Philips Fidelio X1/L1 series of headphones compared to something from AKG: where the Micro is AKG and the Fidelio’s are RSA.  Not that it is a bad thing, just that I feel like a darker background effect really would make the amplifier that much more involving with that forward sense of appeal to the experience.  I think the two would go hand in hand well together, since I cannot think of a single forward sounding amplifier that also has a very black background.  It is very easy to sense the brightness. Lets be honest, it’s not like a Grado or Beyerdynamic brightness, so lets not take it that way, it is just not as jet black as some other experiences I’ve had in the portable world with regard to the space between instruments.  Because of this, the vocal and instrument vividness takes a bit of a hit compared to the top rated amps in the price tier.

I find it to provide something less Audeze, more Hifiman with regard to the bass texture type.  It isn’t a fast and pure sound, I don’t hear that typical reference speed in the Micro.  However, I do hear a more musical approach to the way the bass is portrayed.  The bass lingers a bit on the Micro through my TH600 with tracks like Bassgasm – The Ultimate Bass Test and seems to rumble a fair bit  ( in a good way ) instead of cutting out and being distinctly accurate to the bass in the track.  I’d call this a somewhat musical flavor and presentation, something not at all exaggerated, but also not quite reference.  Clarity is fantastic, no doubt about it.  I’m enjoying the TH600 a great deal when this Micro is paired with my Fiio X3 and Sony A17, it also seems to react fairly well to bass boosting via the source EQ systems.  But, I did notice that the Micro falters a bit at +4dB boost.  Quality takes a nose dive after that, but up to that point things remain strong and in control, which is pretty good.



The midrange is clearly setup for a slightly intimate rig, not at all something I would use with a gently recessed TH600 or similar for vocals, also not something good for the HD650, as things sound relaxed with those types of pairings.  However, my JH16 and Sony 1R, or any similarly forward sounding source and headphone pairing excel through the Micro.  It is definitely that type of presentation I prefer with vocals in regard to physical locale.  It really isn’t common for portable amps to sound quite this forward, by rights my iBasso D42 Mamba and SR71B are actually less engaging than I’d previously thought they were: A/Bing them with the Micro showed just how relaxed they really are.  I definitely prefer the forwardness of the Micro, but I am hearing the same type of lacking solidity factor when I compare it to some other  amps.  It is similar to comparing an electrostatic to a very good dynamic driver, that weighted sound or realistic flare to vocals is less obvious and less distinctive on the Micro than I would like it to be.   I would pair the Micro with great dynamic headphones, but not Planar’s.  I don’t think the weight and solidity factor is quite justified for use with the more solid and firm sounding headphones out there of the Orthodynamic types.


Treble is fairly well extended and again, it makes the amp sound quite deep and aired out.  It might also be the reason some of the upper midrange and vocals in general feel less solid than some other amps in the price tier, but this really isn’t a negative quality.  It is pure subjective preference.  It is still solid enough to sound justified for the price, it is just that the RSA models have an abundance of that solid type of a feel.  This solidity is most noticeable between the two on their top ends, as I’ve found the Micro to house a more loose feel to the entire top end of the spectrum.  Anti sibilant and still of a high quality, but a bit thinner than I prefer.  Headphones with solid treble will play well enough with it, so I wouldn’t worry if you are using something like a Hifiman HE-400 or HE500/560 with the Micro.  You’ll get that good sense of treble, but it will not be the firmest pairing available in the price tier.  It is great, however, to note that the Micro’s top end clarity is more than justified for the price tag, so quality aside, which is very good, the experience can only be dimmed in subjective preferences.  If you prefer a solid, weighted sound, opt for something else.  If you primarily use Dynamic headphones, you’ll be right as rain with the Micro.

Bonus:  The Micro is incredibly powerful.  It rivals my F-35 Lightning from Ray Samuels in output power, which is an amp that in turn outperformed most every other portable amp of any size that I’ve ever used.  The raw power of the Micro on high gain is more than enough to power most Planars ( outside of the Hifiman HE-4 and HE-6 ).  I’ve found myself rarely needing to toggle high gain on and have noticed that the low gain is not only more than sufficient in power output for my full size headphones like the TH600, but also quiete enough to be used with more sensitive iems without sounding overblown.

On a very sad note, the Micro gets about 4 hours of battery life on high gain, taking about 2 and a half hours to fully charge via the wall outlet, a bit longer via the USB  cable alone.  Ouch.

Final Thoughts

The Portaphile Micro is a genre master type of an amplifier, something clearly setup and intended to work well with a wide range of pairings.  It fills a niche for the price range of $300-500 or so and was certainly one of the best performers at this level.  But, it was not the best in the tier, the RSA F-35 still retains the best price to performance value, as well as something that is something I consider “specialized”.  Meaning, the F-35 is dark and not neutral sounding, it pairs better with select types of sounding sources and headphones, where as the Portaphile plays ball with pretty much any rig you want to combine it into.  That may be something to factor into your purchasing decisions…

For now, I think the only real issue I had with the Micro is the lack of a very dark background, but that again is just my preference in sound type.  It seems to make the Philips Fidelio series ( headphones with a super jet black background with my RSA amps ) sound noticeably more illuminated.  This could be a good thing or a bad thing depending on your preferences, again that is because the Micro is more neutral most everywhere and with pretty much all of it’s sound qualities.  As a result, sounds and vocalists do not pop as much as I’d like them to in the sonic void.

No getting around it, the Micro is a professional ball player and able offers very nice price to performance.  I’ve found myself enjoying it a lot with more neutral headphones out there, such as the Sony 1R and similar flat in tone type sound signature headphones.  It didn’t quite steal the top spot for raw clarity or dynamics for the price tier, but it is a peak contender and something you should definitely try to experience should the chance arrive.  I don’t like making direct comparisons or highlighting another product inside a review not about said product, but the RSA F-35 is smaller and has a balanced 4-pin output.  Due to those technical aspects being a bit more user friendly with optional output types, the F-35 will remain in the top spot.  But, note that the Micro is within arms length of the F-35 in clarity.

I would very much like to see Ceasar revise it and directly compete with Ray.  If anyone can, I think it is Ceasar.  The Micro is already quite small, but I would prefer a better output selection with at least one Balanced option.  Right now, just one 3.5mm out and one 3.5mm input is a bit too basic for the price tier.   I am more than willing to sacrifice the battery output power for battery life, in this case a few hours just isn’t going to cut it and I’d rather have a quality battery life experience over something with excessive driving power that drains the battery at light speed.  But, that is just me and my preferences.  I would absolutely recommend it at this price point if you want that middle ground, can do anything type of a portable amplifier.  Good job, Portaphile! This one is a keeper and is easily one of the best $499 or so portable amps that I’ve ever heard.  Near sonically flawless, high marks all around.

Price: $499

Links: http://portaphile.com/shop/portaphile-627-micro-pre-order/

Portaphile Micro Portable Amp Technical Specifications

  • Three Channel Design
  • Isolated Output Ground
  • Four Layer PCB
  • 3 x OPA627 (STANDARD)
  • 1XMUSES01 + 1×627 (OPTIONAL,  50.00 EXTRA)
  • 6xBUF634′s, Jung Multiloop Topology
  • Powered by Single 3.7V Lithium Ion (Battery is rated for 500 Charges)
  • Voltage Increased Internally to over 18Vpp
  • Power Adapter/Charger Included (5V)
  • Runs 4 Hours on a full charge, Battery charges in
  • 2.5 Hours when Amplifier is charged while off
  • External Hi/Low Gain Switch (OPA627 7/2
  • MUSES01 7/1.2)
  • Small Size
  • Elna Cerafine Caps
  • Instruction Sheet