[thuNDa]

  Hello @TheGiantHogweed
 
Thank you for your review. Any chance you could take close-ups of the pcb inside? Specifically, it would help the community to know how the thing is built internally. It would be nice to have close-up pictures of the chips on the PCB. There does not seem to be much information about the amplifier section on this amp. It does state it uses the following chips.
- Digital Receiver : DIR9001
- DAC Chip : PCM1793
- OPA2134 and WIMA caps
 
I am guessing the OPA2134 opamps are used for amplification but is that all they use? Any pics of the internals would be very helpful if you could share them..
 
 
Another thing to note about the specs for this amp: Earphone output power: 65mW @ 16Ω; 130mW @ 32Ω
 
They make no sense, the output increases from 65mW@16ohm to 130mW@32ohm? Output should typically halve when impedance load is doubled..
 
I am looking forward to seeing if this amp can power my Fostex T20v2 cans.. I might order one just to test it out...

 
I made a pic of the PCB:
 

 
 
The HP driver chip is actually a Maxim max97220(close to the white caps at the poti, which you can't read on the pic tho).
 
Other observations i made, are that the Opamp runs at +/-5V(they gained one Volt with some diode trick close to the biggest cap), and that the bass rolloff could be improved with larger caps (again the ones at the poti, which are rated 1uF - i would go for 2.2uF - had some small cap soldered in parallel to one of them and compared the frequency response of both channels).
Originally It's down 1.8dB at 20hz, and 0.7dB at 30hz(tested with RMAA).

 

[speedwheels]

@thuNDa
 
Much appreciated. Looking at the specs for the Maxim MAX97220A, it looks like a pretty basic amp section..hmm. 
 
For anyone interested, Here is the direct link to the specs:
https://www.maximintegrated.com/en/products/analog/audio/MAX97220.html/tb_tab1
 
It does look like the relevant spec is 125mW at 32Ohm.
 
edit: just bought an openbox one on ebay for $38 shipped. Will try it out on my Fostex T20v2 headphones..

 

[TheGiantHogweed]

Here you go:

 

 

 

 

 

 

 

 
The last one didn't work out very well but I don't want to take the thing apart again to take more as it wasn't easy with the tools I had! I haven't used those allen keys before and they seem horribly soft. So soft that they now spin themselves instead of turn the bolts. But I just used the other end to get them back in. At leased the bolts themselves are not soft. The ones on the back require a smaller allen key of the 2 that is shown in the pictures. I don't know much about the insides of amplifiers but hopefully the pictures will be useful for you and others.

 

[thuNDa]

Ah, it's a max9722.
Gives 5mW more at 32Ohms compared to 97220. 

 

[speedwheels]

Great. Hopefully the technical folks around here will find this helpful.

 

[HwGeek]

Thank your for your review, I just got 1 too and I have a question, as you can see the PCB has changed from what you can see in PCB photos of this AMP/DAC, I see that they even changed the capacitors from 470uF 6.3V to 47uF 50V - what affect should this bring? 
mine looks the same as OP's.

 

[TheGiantHogweed]

  Thank your for your review, I just got 1 too and I have a question, as you can see the PCB has changed from what you can see in PCB photos of this AMP/DAC, I see that they even changed the capacitors from 470uF 6.3V to 47uF 50V - what affect should this bring? 
mine looks the same as OP's.

I'm sorry but this is something I barely know anything about so I can't really comment. Others maybe will be able to use my pictures and explain better!

 

[HwGeek]

Can you connect the line out to your PC's line in? I am trying to test it with RMAA to compare my O/B sound card ALC887 on GA-B150M-D3H but when I connect it to PC there is crazy poping/cracking sound from inside the DAC and the 2 leds  going crazy. I am using coaxial input on the dac from my on-board SPDIF.
 
I am very happy with the Amp, finally I can enjoy my Hyperx Cloud (will upgrade LATER).
 
 i am interested to know if I can run it on 12V, since I don't like its cheap PSU that makes ultrasonic niose.
Already running it on old bulky 6.5V DC 0.55A panasonic cordless phone PSU(transformer type) sound same I think-maybe  better Bass but I like to connect it to my PC PSU 12V, got high quality Seasonic psu with low noise, I askes SMSL support, lets hope I can.

 

[Arkye]

Thanks for the review. Can it drive my Superlux HD330? I have to choose between this and the Fiio E10 because I'm currently using the internal soundcard of my pc. I found this DAC at 67€ on Amaz, do you recommend it?

 

[TheGiantHogweed]

  Thanks for the review. Can it drive my Superlux HD330? I have to choose between this and the Fiio E10 because I'm currently using the internal soundcard of my pc. I found this DAC at 67€ on Amaz, do you recommend it?

I think it should comfortably drive 150ohm headphones like yours. Although the E10 is actually slightly louder and as it has a low gain, that gives you more control over the volume when using low impedance headphones that are very sensitive. But considering how much cheaper this DAC is, I would go for it over the E10. It has more inputs and no interference that you sometimes get when using USB audio from your PC.
 
Others may not recommend this S.MS.L DAC though. But I don't know what is better for the price. It certainly should be better than your PC sound card though. You will just either need an optical or coaxial output on your sound card if you want to use this. 

 

[Arkye]

I think it should comfortably drive 150ohm headphones like yours. Although the E10 is actually slightly louder and as it has a low gain, that gives you more control over the volume when using low impedance headphones that are very sensitive. But considering how much cheaper this DAC is, I would go for it over the E10. It has more inputs and no interference that you sometimes get when using USB audio from your PC.

Others may not recommend this S.MS.L DAC though. But I don't know what is better for the price. It certainly should be better than your PC sound card though. You will just either need an optical or coaxial output on your sound card if you want to use this. 

Thanks so much for the fast response. I don't want it to be that loud, but it's more important that this DAC removes the interference my graphics card causes on the motherboard, wich I can hear with the built in soundcard(Realtek ALC1150) and no problem, it has optical output.
Another thing I'm worried about, I have read somewhere that the right channel volume is higher. I hope it's a good DAC over the E10 especially for the price, just want the forum opinion cause yes, I like audio stuff, but I'm not an expert.

 

[TheGiantHogweed]

Thanks so much for the fast response. I don't want it to be that loud, but it's more important that this DAC removes the interference my graphics card causes on the motherboard, wich I can hear with the built in soundcard(Realtek ALC1150) and no problem, it has optical output.
Another thing I'm worried about, I have read somewhere that the right channel volume is higher. I hope it's a good DAC over the E10 especially for the price, just want the forum opinion cause yes, I like audio stuff, but I'm not an expert.

It only has a channel balance issue when the dial is really low. As in with my 32ohm headphones, if I want to listen to them really quietly and I only turn the dial slightly, the right channel is noticeably louder. This is where a low gain switch like the E10 has would be useful so you would need to turn the dial further to get to the same volume. It then wouldn't have the channel balance issue with low impedance headphones. However, with headphones that are harder to drive like yours, it won't have that problem at all as it will need to be turned much further. With my headphones that are 32ohm, it is pretty painful to turn the dial much more than a quarter of the way. So it should be loud enough for yours.

 

[Arkye]

It only has a channel balance issue when the dial is really low. As in with my 32ohm headphones, if I want to listen to them really quietly and I only turn the dial slightly, the right channel is noticeably louder. This is where a low gain switch like the E10 has would be useful so you would need to turn the dial further to get to the same volume. It then wouldn't have the channel balance issue with low impedance headphones. However, with headphones that are harder to drive like yours, it won't have that problem at all as it will need to be turned much further. With my headphones that are 32ohm, it is pretty painful to turn the dial much more than a quarter of the way. So it should be loud enough for yours.

Okay, now I understood it is compatible with my headphones but I'm still confused between this and the E10(or E10k?). The thing I most care about is the fact the SMSL eliminates the hissing sounds coming from the motherboard because it has optical input, but I'm interested on the bass boost and the gain(don't understand what exactly that switch does) the E10 has. Is it really worth having this extra feature if I play games(lot of explosions!) or the SMSL can handle it the same way?

 

[TheGiantHogweed]

Okay, now I understood it is compatible with my headphones but I'm still confused between this and the E10(or E10k?). The thing I most care about is the fact the SMSL eliminates the hissing sounds coming from the motherboard because it has optical input, but I'm interested on the bass boost and the gain(don't understand what exactly that switch does) the E10 has. Is it really worth having this extra feature if I play games(lot of explosions!) or the SMSL can handle it the same way?

The bass boost may be an advantage for some but I don't miss it that much as I just plug my FiiO E11 into the back of my SMSL amp if I'm wanting the bass boosting. All a high and low gain switch does is changes the volume. E.g, on high gain on the E10, it is harder to get the volume where you want it without going too loud or too quiet if your headphones are sensitive. If you are on low gain, it may not go as loud, but it allows you to move the dial more without changing to volume suddenly and it is easier to get the volume you are after. All the E10's switch does is reduce the volume when it is on low gain. The SMSL DAC is already really loud but it just doesn't have a switch that puts it in to low gain. This makes be think it would be impossible to control the volume for a sensitive 16ohm pair of headphones with this. It it fine with mine which are 32 and should also be fine with yours.

 

[TheGiantHogweed]

Oh - the E10K is just a replacement of the original E10. The main differences are that it has micro instead of mini USB as the audio input. The bass boost switch also looks a little different. The inside components are different too i think but not by a lot. I still think the SMSL DAC is better value.