Audinst AMP-HP - Portable Amplifier

REVIEW: Audinst AMP-HP - Portable Amplifier





Full specifications:



WebsiteAudinst

MSRP: U$D 99


Build & Design:

The AMP-HP is very well built for an amplifier in the ~$100 price range. A very solid and compact design, although not slim, and with a rather smooth surface and no sharp ends whatsoever. The volume knob is quite tight, which is a good feature as it prevents a sudden volume jump.
The AMP-HP can only drive 3-pole 3.5mm plugs, so an adapter for mic'ed phones is a must, and the package does not include one. There's a separated power switch at the front panel, but the amplifier won't turn on until both input and output are connected, and the connections are pretty stiff, so extra force is needed when plugging in. A strong sound is heard when the output is plugged, so it's recommended to turn the amplifier on before using the earphones/headphones.


Power, Battery, Hiss:

The 300ohm output power makes the AMP-HP a fair contender in the sub $100 amplifiers available on the market nowadays, as it is meant for the real portable use rather than to power 600+ ohm full-size headphones sets. There is zero hint of hiss even with more sensitive and easier to drive earphones. From testing, the rated battery life looks quite accurate too. Apart from the plug output limitations, there are no Gain or Bass boosts.


Sound:

Being an opamp rolling amplifier the sound should vary depending on the chip in use. The AMP-HP can only utilize a chip at once. The following impressions are limited to the stock opamp.

When it comes to sound quality, the Audinst AMP-HP presents a quite interesting sound and signature than I had expected from a portable amplifier at this price point. It isn't what I'd call a colored sound, but definitely a rather 'flavored' one with certain limitations on its presentation. Both low and high ends are smoothened down and limited on extension and strength, what gives the AMP-HP a more closed and intimate sound. The low end definitely feels rolled-off at the sub-bass region. Mid-bass doesn't suffer as much limitations but still soft and doesn't show any extra lift either. On the other hand, the whole bass is tight and very well controlled for a more relaxed listening. The previous Fiio E11 showed a much darker and warmer sound, even without the extra bass gain, with further extension but sounded more bloated than the AMP-HP.
Similarly, the higher freq. show some limitations as well, but to a lesser degree than at the low end part. Actually, it's very pleasant, not soft and relaxed as the bass, but still well controlled and manages to eliminate serious certain peaks on specific gears. The higher priced Cayin C5 for example is flatter through the whole treble freq., further extended and more revealing, but also not very forgiving with a brighter setup. In comparison, the AMP-HP shows extra emphasis and more thickness on the lower treble section while smoothing down the highest end.

The midrange is obviously the most important part of the AMP-HP. Forward and rich mids with a smooth and engaging flow with a slight brightness towards the upper midrange region. Vocals are closer, charging more body and nicer texture, extra energy and emotion. And one thing is sure, when well paired, the vocals are really good. The details aren't as clear as with the more analytical C5 amplifier, but the AMP-HP is more forgiving overall.

Soundstage and dynamics, as expected, are not the strong points. It will improve the overall sound of more entry sources such as the Sansa series but when matched with a mid-fi source as the HM-700 it will actually change the DAP wide and spacious sound into a noticeable more intimate presentation and limited in extension. Even though, it's worth mentioning that the vocals are quite great on the HM-700 + AMP-HP combo.

Synergy-wise, it isn't an all-arounder either. Among some gears that achieved best results when paired with the AMP-HP are the Senn HD600 and HD650 full-size open cans. Although the large soundstage gets limited and both extensions roll-off earlier, the sound is intimate and with a more attractive midrange with sweet and upfront vocals. Sibilance is practically not present as well.

In-ear sets such as the R-50M and both Hifiman RE400 and RE600 also showed very nice results on the midrange with better articulation and texture than from a Clip+ or Zip and different flavor than from the HM-700. But then again, stage and depth is smaller and not very inspiring. On the other hand, the very mid-centered Fidue A63 showed a bad synergy; too thick mids close to being veiled, losing the whole A63's magic. Interestingly enough, the Ostry KC06A which tend benefit from good amping showed certain sibilance that wasn't present with C5; probably due to the extra emphasis on the lower treble of the amp.




Conclusion & Value:


All-in-all, the Audinst AMP-HP is a much flavored sounding amplifier with limited synergy capabilities. It probably would sound better/different with other opamp chips. There're some things that it does very well like the midrange, and a more relaxed sound overall. It's very well built and very portable too. It is a fair contender in the sub $100 portable amplifiers and the opamp rolling option is always a plus, but still has some hardware limitations to really shine.