Alientek D8 headphone amplifier and DAC
Dec 13, 2017 at 7:09 PM Thread Starter Post #1 of 3

Joong

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I recently bought this little amp/dac in XMOS version (U8 chip as found in Gustard U12 DDC), which is already well known for its performance / cost ratio among countries like South Korea and China.
One of the reviewers said this was so well matched to his AKG K702s and mdr-1rbt mk2.

"The spec is too good to be true", which was one of the response from one of headfiers.
Indeed it is partly true when I plugged my phones to it and play some Mahlers and Stravinskies.
I have been used to smooth sounding dac based on AK4497 based ones like Gustard a20h.
But this dac / amp reveals raw nature of sound with deep sub bass and well extended highs.
I realize the mids are very good as well when I listened to the adagio section of the organ symphony of Saintsaens, which was lushed and smooth.
In comparison to the Gustard, the sounding through Fidelio X2 is surprisingly crisp and detailed.
The sound quality is not necessarily better, but has definitely different flavor of my Gustard, which is far expensive unit.

Th900 MK1 and Sony MDR Z7 seemed generating more raw-ish sound with surprising dynamism.

One drawback is that the power of headphone amp is not enough to drive inefficient phones like high impedance phones (more than 300 ohm) and current hungry planar phones, but it has enough good power for my phones.

One noticeable thing for headphone amp power is that even though the power is declared as 130mW at 32 ohm, the actual power is far more than that when I compared to Fiio Q1 mk2 rated as 220mW at 32 ohms on the balanced output or to Xduoo x10 rated 250mW at 35ohms. My hearing via X2 or Nightowl (30 or 25 ohm) from this unit is far more than that (perhaps more than double). There must be some error in spec either on Fiio or D8.
This apparent stronger output might be due to higher rail voltage (27 volt) of the system than those battery powed devices.
The highest impedance phone of mines is Sony mdr z7, which was tested for this apparent power. But result is the same as my other phones.
In order to compare output power of headphone jack, the volume counts of Gustard a20h were matched to the same, and my hearing is almost matching, that is a bit surprising because there is big difference in power between the unit and the Gustard which has more 2.4 watt at 32 ohms.
I am almost tempted to buy 300 ohm-phones like HD650 or higher one DT990-600 ohm for testing.
This dac/amp continues to surprise me! I never reach beyond 50 counts in any of my phones due to unbearable loudness of sound!

Probably the statement of "One drawback...the power...is not enough.." is not verified one but is written based on the spec!

[edit Dec/23rd/2017] The amp section seems to reveal finally its limitation of the integrated amp of MAX9722 when the most complex passage in "dance of the king" in Rite of spring of Eiji Oue's Minnesota Orchestra, where full-orchestra engagement under huge sub bass rumbling, and there is strong inter-modulation of sub bass with every other frequencies. This might be due to the lacking of instant power that depends on the size of transistors and supporting capacitors for cash power; where the small foot printed electric circuit shows its limitation to decouple the ranges of mid/highs with sub bass section.
However, it is only one musical passage among so many listening to so much of the music collections of my library. With this regard, it is acceptable limits which can be easily ignore-able when I listen to without intense focusing to the performance of the amplifier.

One of the noticeable features is the connectivity having interface of RCA analog, coaxial/optical/USB, especially USB through XMOS U8 is impressive in terms of the sound quality.

This unit has also have good T-class amplifier with 80 watt per channel, but I did not have much attention for the quality of that department.
I think it can compete against those of Teac AI series dac/amp series like Teac AI 3xx, or 5xx.
However it might be one welcome feature for those who are looking for small foot print for already complex desk space.

[edit dec/21st/2017]: One of the purposes of this dac/amp was to drive onefficient phones through speaker taps in order to overcome the rather the declared weak output power of the amp section, but there is noticeable noise.
However all my current phones (X2 / Th900 / Nighthawk/owl/ MDR Z7 / Superlux HD668b) are well driven so that I could not reach 50 counts of 100(? never reached beyond 50 due to high volume).
In the mean time I had SMSL Idea, and Fiio Q1 mk2, but I returned them back, because they are all inferior to this dac/amp section.

Only comparable one is my Gustard a20h which seems better for Nighthawk/owl perhaps its having balanced output(?), the Gustard is not necessarily better but at least no more attractive than Alienteck D8 for its details and highs/lows.
For sub-bass section with Fidelio X2 is so deep and rumbling that the mids/highs of final section Fire bird of Stranvinsky is strongly coupled and modulated producing highs cutt-offs at extreme low sub-bass-reaching in the most complex passage of the full orchestration.
I tried the same section of the music with other phones except HD668b, there were no such coupling.
However Fidelio X2 is incredibly well matched with the amp, now X2 is the most enjoyable phones.

I should mention the remote is quite useful for volume / bass / treble / mute that muting speaker with / without phone activation/deactivation.

The amp section was also tested with A20H as dac, and the sound quality is noticeably better than Fiio Q1 mk2, and not worse than that of A20H or my KRELL KSA5 knock-offs.

The manipulation through volume contol knob is intuitive and pleasant, which is more like mouse function for example one click for main menu pop-up and rotating for selection, and double clicking for optional feature pop-up and the rotating for selection with one clicking for off the menu.

The chain of devices for testing: Windows 10 /foobar->ifi nano USB3.0->Alientek D8->X2/th900/mdr z7/Nightowl-carbon

Here are some links regarding Alientek d8:

https://www.audiophonics.fr/en/full...-xmos-class-d-2x-50w-8-ohm-black-p-11358.html

.https://www.aliexpress.com/item/Ali...-eac1-475e-bf50-44ce040f02e3&rmStoreLevelAB=0

Conclusion:
Despite its limitation instant power in very intense and complex passage under strong sub bass rumbling, the amp section can be considered excellent while the dac of PCM5122 can be considered very good throughout all the listening period. The highs and lows are better than any dac that I had.The result is better being focused and detailed.
It is especially amazing in that even though the integration chip implemented amplifier the power is enough for all the loudness level of my preference through from 25 to 70 ohms phones.

The commercial summary:

Amplifier Class D ALIENTEK D8 Full Pure Digital HiFi Stereo Amplifiers USB Coaxial Optical Audio Power Amplificador PCM2704

Input Interface:USB Fiber Coaxial Analog RCA

Output Interface:posts 6.5mm headphone output

Output Power: 80W*2@4Ω 80W*2@8Ω Headphone output power:130mW@32Ω

Sampling Rate:44.1Khz-192Khz XMOS/USB/Fiber/Coaxial

44.1Khz(PCM270USB) 96Khz(Analog RCA)

ColumnWidth:16bit-24bit

Frequency range:18Hz-22Khz

impedance:4Ω-8Ω

SNR:amplifier:100dB Headphone Amplifier:112dB Dynamic Range:amplifier:100dB Headphone Amplifier:112dB

THD+N:amplifier:0.05% Headphone Amplifier:0.003% Power:172W(Max)

Size:140*108*32mm

Weight:1.2kg

Power Adapter: 28V 4.3A
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Apr 17, 2018 at 9:53 PM Post #3 of 3
I sold Gustard a20h, and keep Alientek D8.
[edit]
Because I need more desk space, and have no more high power planars.
The Gustard was very good for those phones, whereas Alientek D8 is good enough for driving my dynamic phones like TH-900s, Sony MDR Z7s, Nighhawks, and Fidelio X2s.

The ability of control over treble and bass is what I need for V shape nature of those phones of Th-900s and X2s.

Especially its synergies with X2 is exceptional ones to me.
This hobby is weird world of subjectivity, and diversity, where every opinion might be justified.
However I can say that Alientek D8 is indeed a hidden gem.
 
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