Audinst AMP-HP

General Information

compact portable headphone amplifier

Latest reviews

Pros: Great Sound Quality, Build Quality, Battery Life, Muses 8820 Op-Amp
Cons: Driving Power

Me: I am a 21 year old Engineering student living in a small town in India. I would like to call myself a music enthusiast, rather than an audiophile. I was inspired by music since childhood, and as the time passed, the passion of music grew in me, and that subsequently led me to join Head-Fi. Eventually, I found the pleasure of listening to music mainly by the HD600 and recently, by the seductive LCD2 headphones, and realized the true components of recorded music. I usually like to listen to Indian Classical Music along with Bollywood songs. My main listening genres include classical, vocal, instrumental, jazz and sometimes pop.
Intro:  Audinst, is a renowned Korean amp/dac manufacturer. They are based in Incheon, South Korea. The brand was established in 2009. All their products are made in Korea. Amp-HP is their lone offering in portable amplifier category.
Specifications of Amp-HP as per Audinst:
Input: 3.5mm
Output: 3.5mm headphone Jack,
Maximum power output: 300mW @ 32 Ohms
Headphone Impedance: 16-300 Ohms
Output Impedance: 5 Ohms
Input Impedance: 11K Ohms
Battery: 800 mAH 3.6V
Weight: 134 grams

Let us see what the Amp-HP has got for us,
Packaging and Accessories: The Amp-HP arrives packed inside a large colourful cardboard box, on which features and other information have been mentioned upon. Once the box is opened, the main unit and all accessories are put in a typical packaging.  Accessories are found beneath a pseudo-bottom compartment. No complaints here. Nothing special to mention about either; all accessories have a good quality, build and feel to them. The accessories are made in Korea too.
List of accessories in the box, which include the following: 
Power Adapter: Standard 15V 1A DC power supply for recharging the Amp-HP.
3.5mm Interconnect: Standard white coloured 3.5mm cable, about 20 cm lengths.
iPOD Cable:  Audio cable specially for ipods of 20cm length
Pouch:  A soft velvety pouch to store the Amp-HP.
Rubber Feet: For attaching to bottom surface of Amp-HP, thus making it scratch and skid resistant.
User Manual: Detailed and informative Instructions about operation, also contains warranty information.

Design and Build: The Amp-HP has a very good overall build quality.
The outer case is made up of aluminium, and is painted in greyish silver. Front panel is black coloured; volume knob is rubberized, and has a grippy feel to it. In pictures Amp-HP looks larger, but in real, it is quite small.
On the front side, we have Volume control knob, an on/off switch and a output headphone jack in 3.5mm format. An LED indicator shows the status of operation. 
On the rear side, we have 3.5mm input jack, along with DC power input jack.
Speaking of Internals, Amp-HP has a double sided PCB with no wirings. All components used are of good brands; including all dale resistors, Alps pot, premium caps. There is only two user replaceable parts on board the Amp-HP: Muses 8820 with DIP8 socket other op-amp is AD8397 and is permanently mounted SMD. Audinst has always been a strong contender in the field of Build, interiors, components and PCB.
Battery life on Amp-HP is very good (considering its output power), which lasting about 10-12 hours. And recharging time is just about 2 hours. Its gets slightly warm during charging process.

Sound:  I feel the Amp-Hp is neutral, detailed and slightly smooth in sonic presentation. Sound-stage width is moderate. Depth is pretty good. Absolutely zero audible hiss/noise.
Lows are strong and accurate and goes very deep. Infact, it’s rare to see such good quality bass in sub 100$ portable amps. Mids natural and clear, slightly intimate if I must say; Highs are smooth and non grainy, just right amount of sparkle to keep the music alive.
Soundstage on Amp-HP is very good, and realistic and for some, lacking in width. Depth is fair. Amp-HP does not give a circular imaging, instead gives out an elliptical stage (with comparatively more depth and lesser width) Detail retrieval, and dynamics are decent enough. Overall he sonic presentation is very much like-able. Also, the final sound impressions of Amp-HP can be manipulated by using different op-amps.  I have changed to Op-Amps and I could observe that the current op-amp (MUSES 8820) does a very fine job, and I feel there is no need for op-amp rolling to increase sound quality.
Comparing the Amp-HP with JDS Labs Cmoy, I feel the Amp-HP audibly outperforms the latter. Amp-HP is slightly thicker and smoother, whereas Cmoy is thinner and feels more transparent, with wider soundstage.  Although the Amp-HP clearly wins in design, build quality, utility and features; Amp-HP & LCD2’s have a good synergy going between them, but It is definite observation that Amp-HP lacks power to comfortably drive them.

Conclusion:  Amp-HP is a great sounding amp in its price point, especially the sonic performance of lower frequencies is the best one can get in sub 100$ portable amps. This device is actually pretty great on features and practical aspects. At the price point of 99$, Amp-HP stands right in the middle of a 70$ Cmoy and a 130$ O2. Amp-HP like an intermediate between the two. Sound quality is definitely better and well defined than a JDS Labs Cmoy, but not upto the Objective2 level.
I can recommend Amp-HP for any music enthusiast who want a handsome and fine sounding portable amp to drive low impedance headphones.
The Pros: 
1) Design and Build: Amp-HP has very well designed and implemented build and intelligent three way on/off feature.
2) Sound quality: I very much like the sonic presentation on this little amp, I can describe it as slightly thick, smooth and pleasing, and might I also mention the intimacy. A very fine sounding op-amp Muses 8820, I can imagine it would pair well with almost any headphones.
The Cons: 
1) Output Power: Output power at headphone jack is about 300mW @ 32 ohms, which seems quite good on paper. But in real, it is insufficient to drive power hungry headphones. So, this will limit Amp-HP’s usage to IEM’s and easy-to-drive headphones.


YoYo JoKeR
YoYo JoKeR
Sure they are, but does the 5 ohm out Impedance make an audible difference in driving the BA IEM's?
To me, BA IEM's audibly sounded fantastic.
My point is not that high impedance will ruin the sound, it will just change the sound signature. IEMs that are good will still sound the fantastic it won't destroy the SQ, just the signature or frequency response due to loading.
Bass will sound more pronounced and punchy on low out-impedance sources than on higher ones whereas recessed mids will be a little forward on high impedance sources compared to lower ones. The sound quality though will remain unchanged.
YoYo JoKeR
YoYo JoKeR
I did not perceive any such issues. Sound signature and presentation (Lows, Mids, Highs) of the IEM remained intact. The only coloration present in the pair was due to Muses 8820 Op-Amp.
Pros: Well built, pleasing sound signature, lots of accessories, won't break the bank, socketed opamp allows playing with the sound
Cons: Could use more battery life
You're saying this is better than the HUD-MX1?
In many situations, yes.


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