述而不作，以防止我的翻译不当，仅原文实录。我上穷碧落下黄泉，找到了这些评论，出处headfi。
I am looking at buying a Cheapish DAC to feed my Little Dot MKII and I keep being drawn to looking at the NG94 MKII PCM1794 USB&SPDIF DAC+Headphone Amplifier AMP on ebay . Mainly as it's got USB, Coaxial (BNC/RCA), Optical and the DAC module is on a seperate board and so might have upgrade possibilities ... Has any one got the MKII version ? How good is it ?
I want to own that one, the good specs is the first impression
Definitely good specs for the price. But it's just on paper or real?
I'm inclined to say it's on paper.
I can't properly test it without attenuation, the output overdrives my amp; and it would fry Essence STX's 2 vrms unprotected line in.
The results were unspeakably bad using 12db harrison attenuators (3 vrms -> .775), but that's way too low for the adc on Essence, perhaps it greatly influenced the signal.
The results were like 80-87db snr/dynamic, .05? thd/imd, -66db stereo seperation ... didn't even bother to save results it was so bad. It was dropping off the low frequencies a lot, too. RMAA showed the peak of the test tone at -10db - so perhaps this card's real snr is 90-97db? Still bad thd/imd, and only 16bit performance if that's the case.
Hopefully someone with a better ADC that can handle its output will test this dac. I probably shouldn't have gambled on an almost unknown chinese product.
Definite cons to this dac, which are silly for its price range IMO:
-You will in all likeliness need an input volume control if you use the line out unless you want to overdrive or possibly fry things.
-Line out and headphone out can't be switched, they're always on.
-No balanced output - little dot dac_i plz?
-Can't easily swap in better, lower thd/noise opamps like LM4562.
-USB input not asynchronous
Anyways, my review:
Speakers: a dac sounds like a dac. seriously.
Headphones: My A900's don't need an amp, they need an attenuator, and the volume knob on this works nicely for that, letting me use windows volume at 100%...
Update: Wow, no more chinese junk for me. Just a few days of ownership -> left channel cuts out.
The build quality looks pretty bad, there's blobs of clearish white stuff making a mess, and a lot of solder joints look like they weren't even soldered.
Stay away from HA-info.
That's so bad. Thank you for impressions. You just saved me and may be couple of people too.
I was curious if my attenuators were the problem, hoping that I didn't get totally screwed. Turns out I was indeed screwed.
The attenuator does lower the snr a bit, but its transparent: see for yourself.
The volume was at -9db from the Essence using attenuator, and -4db from the NG94 MKII. So the NG94's SNR should technically be 5db lower compared to Essence.
Measured it again since it mysteriously started working properly again.
The NG94 specs are really weirds :
3VRMS for line-out (standard is 2V).
9VRMS for headphones.
Look like an headphone/preamplifier frying machine :)
I know in france there is a vendor who is selling the NG98 (an other model) and there's no problem signaled on this device.
And the specs aren't the same (it's cheaper) :
- 2VRMS for line-out.
- 7VRMS for headphones.
- Line-out isn't RCA but mini-jack.
- DAC chip isn't AD1955 but AD1852 or CS4398.
Perhaps your device is a faulty device ?
Who knows, maybe it was faulty, I'm not going to gamble the same device twice..
The 3 vrms line out is very suspicious. It should have clicked in my head before I bought it.
The HA-info rep said the 3 vrms was to "raise dynamic range", and yet it would seem it only has ~100db @ unattenuated 3 vrms (basing this off the Essence's snr drop when using the attenuators).
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Post By：2012-3-10 22:28:54 [只看该作者]
