Audinst AMP-HP: impressions and reviews
Aug 6, 2011 at 1:48 PM Post #46 of 74
Okay, so I got to listen to the AMP-HP a bit at a headphone store today, and it's definitely quite good for the price. The bulge protrudes a bit more than it seemed in the photos, but I personally don't mind. It was able to drive 32 ohm DT880s and DT990s quite convincingly, being fed the line-out from my HiFiMan HM-601. The sound is slightly warmer than neutral, and the bass punch is nice - much like the MX1, but slightly more refined to me, possibly because of the superior source. I also like how the power turns on/off automatically when the headphone is plugged/unplugged. Seems like a winner to me.
 
Aug 13, 2011 at 9:04 AM Post #48 of 74
I'm here!
 
I'm just finishing up my review on this amp. Hope to post it within the week. It's a very impressive little amp and I'm surprised there is not more discussion about it..... considering the HUD-mx1 has become very popular, I thought people would jump on the next release from the company. 
 
Aug 20, 2011 at 5:12 PM Post #50 of 74
Aug 20, 2011 at 7:11 PM Post #51 of 74
Great review as always, project86. Now I want one too - partly for brand loyalty, partly for my HD25s. Haven't heard from Austin Morrow in a while...
 
Aug 21, 2011 at 10:06 PM Post #53 of 74
Thought I would translate and summarize some of the reviews the amp has been getting in Japan.
 
First from kakaku.com (Japanese deal/price aggregator). The AMP-HP gets an overall 4/5 stars:
 
====
 
マ・マ writes that he's not sure who the amp is tailored towards, or who he could recommend it to. For those who are used to, and like, rolling opamps he would recommend buying the iBasso D2+ at the same pricepoint. The slight bump on the amp comes in for some criticism, but he/she admits that after 3 days one quickly gets used to it. The battery also could be better in their opinion, perhaps deploying the 006P rather than the stock battery - a change which improves the sound quality in their opinion. 
 
So for those who don't mind the hump, don't mind rolling opamps and don't have a large portable collection or want to build one, this amp may be for them. It is the cheapest rollable portable (in the Japanese market) and for not very much outlay the outputted sound can be changed quite dramatically. 
 
The stock MUSES8820 is a little boring (in their opinion) and the resolution merely adequate
 
MUSES02 lets the top end soar in comparison to the 8820, and tightens up the sound, but at the loss of some emotionality in the sound.
 
LME49860 is their top recommendation. Separation is good, and the sound becomes clear-cut/ 3 dimensional. Overall, clarity and detail are improved, without any feeling/impression of "edginess"
 
LME49720 is grainier than the 49860 and not worth buying over the 49860
 
OPA2134 is very energetic and lively, but because of this it may not suit all kinds of music
 
OPA2277 is more restrained than the 2134 but doesn't suit the AMP-HP very well
 
So even with the drawbacks re:shape and battery and stock opamp he/she does like it very much. 
 
====
 
Kenzo Konoike was using the AMP-HP to power the Shure SRH440 (44 ohms) with the iPhone 4 headphone out as a source. Compared the sound through the amp to the iPhone jack the sound is clearly  better in quality, and the driving power of the amp shines through. The lower end of the Shure is extended (about an octave) but in a pleasingly composed and assured manner. 
 
When running the SRH440 out of the iPhone, the lower end does bleed into the midrange especially on songs with a driving baseline, but the amp does a good job of improving the separation of the mids from the bass. He also notes that the amp may match better with phones of higher impedance as the gain is a bit much for the SRH440. 
 
As for opamps, the MUSES8820 is quite good, but in comparison the MUSES02 is a little more mature, but lively in terms of sound (he writes the sound gives a feeling like water bubbling energetically out of a pipe). The lower end does extend down further and vocals in particular sound more harmonious/melodious. The soundstage widens out nicely, with improvements in positioning and location of instruments, and so the overall "live" quality of the sound gets better.
 
===
 
Hope this has been helpful!   
 
Aug 22, 2011 at 2:05 PM Post #55 of 74
Not a problem project86! I thought the info about opamp rolling would be useful to have posted here. I'd love to hear what you think of the LME49860 when you get the chance
 
Sep 7, 2011 at 12:20 AM Post #56 of 74


Quote:
マ・マ writes that he's not sure who the amp is tailored towards, or who he could recommend it to. For those who are used to, and like, rolling opamps he would recommend buying the iBasso D2+ at the same pricepoint. The slight bump on the amp comes in for some criticism, but he/she admits that after 3 days one quickly gets used to it. The battery also could be better in their opinion, perhaps deploying the 006P rather than the stock battery - a change which improves the sound quality in their opinion. 
 
So for those who don't mind the hump, don't mind rolling opamps and don't have a large portable collection or want to build one, this amp may be for them. It is the cheapest rollable portable (in the Japanese market) and for not very much outlay the outputted sound can be changed quite dramatically. 
 
The stock MUSES8820 is a little boring (in their opinion) and the resolution merely adequate
 
MUSES02 lets the top end soar in comparison to the 8820, and tightens up the sound, but at the loss of some emotionality in the sound.
 
LME49860 is their top recommendation. Separation is good, and the sound becomes clear-cut/ 3 dimensional. Overall, clarity and detail are improved, without any feeling/impression of "edginess"
 
LME49720 is grainier than the 49860 and not worth buying over the 49860
 
OPA2134 is very energetic and lively, but because of this it may not suit all kinds of music
 
OPA2277 is more restrained than the 2134 but doesn't suit the AMP-HP very well
 
So even with the drawbacks re:shape and battery and stock opamp he/she does like it very much. 
 

 
Hi WestLander, et al,
 
I am really, really new to all this, but I was intrigued by the suggestions at swapping parts out to improve the sound of the AMP-HP (mine should be here in a week or so) and I began researching some of the parts. Interestingly enough, the LME49860 appears to be available from Digi-Key for $4.34. It appears from the pictures posted by Project86 that this would be a simple plug-and-play operation. Is this the case?
 
My real question, though, is that the only battery options I find listed with a part number 006P is a standard 9v rectangular battery. If there another form of 006P that I am not seeing, and if not, are they simply suggesting removing the rechargeable battery and replacing it with a 9v?
 
I hope these questions aren't completely ignorant, but I won't learn unless I ask. Thanks for any input!
 
 
Sep 7, 2011 at 10:50 AM Post #57 of 74
 
Quote:
 
My real question, though, is that the only battery options I find listed with a part number 006P is a standard 9v rectangular battery. If there another form of 006P that I am not seeing, and if not, are they simply suggesting removing the rechargeable battery and replacing it with a 9v?


I took another look at the 006P battery swap mentioned in the review, and it seems like he or she is saying that if Audinst could have adjusted the design of  the amp, (and in doing so, remove that hump), they could have fitted a higher capacity battery which would improve sound quality. The form factor is different from the stock battery so I'm not sure if it would fit in the current case. There do appear to be rechargeable versions of the 006P, available as the PP3
 
 
Sep 9, 2011 at 3:28 PM Post #59 of 74
I've had my AMP-HP for only a day now, so these are only initial impressions without any real burn-in time. I've run the amp out of my MacBook Pro and my T-Mo G2x (LG P999) phone. Haven't put it on my iPad or iPod yet. My reference headset is my trusty Senn HD280's. I know a lot of people don't like these cans for one reason or another, but I have had my pair for probably 7 or 8 years, and have no issues with build, comfort, or sound. I have also tried them out with a brand new pair of ATH-M50s (no burn in on them yet either).
 
Overall I think the amp does exactly what I wanted - it cleans up the highs a bit and has no huge impact on the overall sound. It does not push the highs, or make them unbalanced. It simply seems to make them sharper and thus increase the detail available. (It even manages to do this on a set of Phiaton MS 400 cans that I am pretty excited to send back as a failed experiment in allowing my eyes to buy something that are meant for my ears... but I'll say more about that in the proper place.) In other words, I think that the sound output is very neutral, but does bring out the detail in the highest-mids to the highs, while not being detrimental to the lows in at way. For me, this is pretty much perfect. :)
 
I think that the AMP-HP will serve its purpose well for days that I want to run my M50's a little cleaner, and will probably find its way into my bag for most flights, and will be a stock part of my very new and small desktop audio gear collection. It will also be a great platform for whatever my next can upgrade is, even if that is a long way off in the future.
 
@dachness: After I get everything burned in and get more used to the sound on the AMP-HP, I'll order an LME49860 and see if I can tell any difference. I am not sure that my ears are trained enough to tell a real difference, but we shall see.
 
Sep 9, 2011 at 4:10 PM Post #60 of 74


Quote:
@dachness: After I get everything burned in and get more used to the sound on the AMP-HP, I'll order an LME49860 and see if I can tell any difference. I am not sure that my ears are trained enough to tell a real difference, but we shall see.


Thanks 
smily_headphones1.gif
. Very interested to see how they are with ATH-M50. Looking for an amp for iPhone4 and ATH-M50. Sounds great with iPhone4 currently but as usual I wouldn't mind increase SQ. If you have a chance to compare iPod/iPhone headphone out vs the amp and a LOD it would be appreciated.
 
 
 

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