Review and Measurements of SMSL SP200 THX HP Amp

[taylptrsn]

788 is certainly good enough. Unless you use very sensitive iems you won't hear a difference.

I may buy one of these "Cheap" Hifiman HE6se's and wherever I go people say they can take as much power as I can give. So I was just exploring the best non power amps available. the .8W difference into 50ohms is probably not worth buying a dac etc...

 

[JohnYang1997]

I may buy one of these "Cheap" Hifiman HE6se's and wherever I go people say they can take as much power as I can give. So I was just curious. the .8W difference into 50ohms is probably not worth buying a dac etc...

First of all the statement is certainly false. The power is defined by the listening volume. Even when there's strong emf from the headphones, low output impedance from these amps will certainly absorb it.
I had listened to he6se in the store. I tried dongle db magix ac3, I tried my own amp, I tried another amp. Minimal difference. It will make a difference when you listen at very high volume. In that case 887 may make sense. But ad8397 already has pretty high output current so I don't think you would be hearing a difference if level is matched.

 

[trl]

As noted, we don't get more power using XLR output. That is fine with me. There is no benefit to "balanced output" anyway on headphones. And we have tons of power here, albeit less than what the Drop THX AAA 789 can produce.

28 pages here, probably this has been already said, but worth an update: reason for having the exact same output power when switching from unbalanced to balanced is that the amp itself is not fully balanced. There is an OPA1612 at the RCA inputs which takes care of both Left & Right unbalanced signals, and for the balanced XLR inputs there're 2 x OPA1612 that are converting the unblanced for feeding the OPA564.

Seems that @yummy already "discovered" this here, but also other ASRers found this info as well, although worth mentioning again Benchmark's thoughts about balanced headamps: https://benchmarkmedia.com/blogs/application_notes/audio-myth-balanced-headphone-outputs-are-better:

"Benchmark does not offer voltage-balanced headphone outputs on any of its products. The reason for this is that a voltage-balanced interface serves no useful purpose when driving headphones. The truth is that a conventional single-ended headphone drive is technically superior to a balanced drive. This paper explains why single-ended headphone amplifiers are inherently more transparent than balanced headphone amplifiers.
[...]
We do offer a 4-pin XLR connection on the HPA4 headphone amplifier, because this 4-pin connection offers lower contact resistance than a traditional 1/4" TRS connection. For performance reasons, this connector is not driven with a voltage-balanced signal. Instead, it provides isolated left and right ground returns that are individually connected to the ground reference points in the left and right amplifiers.
[...]
Please understand that Benchmark strongly encourages the use of balanced line-level interfaces between audio products. All of our products are equipped with fully-balanced XLR analog inputs and outputs. In these box-to-box line-level connections, a balanced interface can provide substantial performance improvements. Balanced line-level interfaces reject hum and noise while providing a higher voltage level. The higher signal levels can improve the SNR (signal to noise ratio) of the audio system".

I'm personally only 90% inclined about what Benchmark engineers says, but I'm sure they're right.

As a side note, THX 789 has two output buffers per channel, the same OPA564 operational amplifiers, but each one is used to amplify the "hot" signal from the balanced signal.

However, like Amir stated, SP200 has enough output power and it has an extremely low-noise, so as long as this headamp can accept balanced interconnects (it's hard to pass 10m long with RCA cables and not inject some of the noise), then the most important aspect of purchasing a balanced amplifier is already achieved.

Some photos I found today on apos website: https://apos.audio/products/smsl-sp200-thx-headphone-amp. Seems that @Veri found this website too, so I'll provide direct links from their CDN servers:

 

[Keelo117]

Got it after what seemed like forever.

Dx3 pro with this amp is all that one needs. This setup with the quality of sound it produces should be 5 times its price in my opinion seriously a good time to be a audio head

 

[or965]

@amirm First of all, thanks you so much for this detailed review of this AMP .I did not understand some things about the measurement and I quite confused about the difference between using balanced and single ended DAC with this AMP .
I saw that you measured high gain of 11.1 db but SMSL spec is 18 db .Is the gain change between balanced and single ended input ?
I want to know if I will get lower power then you measure when I use single ended DAC with output of 2 VRMS and between using balanced DAC with output of 4 VRMS .Also I want to know if you test the power of the AMP with XLR input of 4 VRMS .

 

[thekenta]

Amazing review, thank you.

As someone new to the AMP game, I was wondering whether I should go for the JDS Atom or the SP200 as my first headphone amplifier.
If I was living in the US, the Atom would be an easy choice for a novice, but here in Europe, the price difference isn't that steep.
An Atom would cost me 160€ while I can get the SP200 for around 260€.
The Topping D50 would function as my DAC.

Any help would be greatly appreciated.

 

[JohnYang1997]

Amazing review, thank you.

As someone new to the AMP game, I was wondering whether I should go for the JDS Atom or the SP200 as my first headphone amplifier.
If I was living in the US, the Atom would be an easy choice for a novice, but here in Europe, the price difference isn't that steep.
An Atom would cost me 160€ while I can get the SP200 for around 260€.
The Topping D50 would function as my DAC.

Any help would be greatly appreciated.

I recommend atom or directly go monoprice 887.

 

[amirm]

@amirm First of all, thanks you so much for this detailed review of this AMP .I did not understand some things about the measurement and I quite confused about the difference between using balanced and single ended DAC with this AMP .

My pleasure. On your question, if you can, get a balanced DAC to drive it using XLR cables. That way you have a lot more immunity against ground loops. Balanced DACs are pretty cheap these days so that pairing makes sense to me. That said, ground loops are rare so if you want to get an unbalanced one, that would be OK too. But be prepared to return it if you experience hum/buzz.

There is no audible difference between balanced and unbalanced if there is no ground loop.

 

[or965]

My pleasure. On your question, if you can, get a balanced DAC to drive it using XLR cables. That way you have a lot more immunity against ground loops. Balanced DACs are pretty cheap these days so that pairing makes sense to me. That said, ground loops are rare so if you want to get an unbalanced one, that would be OK too. But be prepared to return it if you experience hum/buzz.

There is no audible difference between balanced and unbalanced if there is no ground loop.

I just received it yesterday and contact it with my topping d50 with USB to my PC and Samsung adapter for power . Unfortunately I hear hiss and buzzing noise when I use earphones.I tried to use toslink and the buzzing is gone but still has hiss noise .I also have the objective 2 amp and with the same setup, USB to PC and Samsung charger has no hiss and buzzing sound.If I will buy a balanced DAC,it will solve the noise issue or it is a defective amp.

 

[amirm]

I just received it yesterday and contact it with my topping d50 with USB to my PC and Samsung adapter for power . Unfortunately I hear hiss and buzzing noise when I use earphones.I tried to use toslink and the buzzing is gone but still has hiss noise .I also have the objective 2 amp and with the same setup, USB to PC and Samsung charger has no hiss and buzzing sound.If I will buy a balanced DAC,it will solve the noise issue or it is a defective amp.

Hissing tends to indicate a problem with the amp. You do have a ground loop though for which Toslink is an effective control, or you could use a balanced DAC (or both).

 

[or965]

Hissing tends to indicate a problem with the amp. You do have a ground loop though for which Toslink is an effective control, or you could use a balanced DAC (or both).

The hiss noise happens only with earphones and not with headphone like the hifiman 4xx. I will probably return it as it does not happens with the objective 2 amp and drop thx 789 amp of friend of mine.

 

[Veri]

The hiss noise happens only with earphones and not with headphone like the hifiman 4xx. I will probably return it as it does not happens with the objective 2 amp and drop thx 789 amp of friend of mine.

I don't have hiss with mine on low gain, only on high gain.

 

[or965]

I don't have hiss with mine on low gain, only on high gain.

On the hifiman 4xx I do not have noise even on the high gain but with earphones ,I have hiss on low gain at low volume and increase as I move the knob.

 

[Veri]

On the hifiman 4xx I do not have noise even on the high gain but with earphones ,I have hiss on low gain at low volume and increase as I move the knob.

If it increased with the knob and is not constant it likely comes from your source over the RCA cables. Don't think the amp is at fault here.

Then again if it doesn't happen with same set-up with the O2... odd.

 

[mks]

I'm using a SMSL m300 connected to the sp200 via rca to xlr cable ( https://www.amazon.com/gp/aw/d/B077YL2J8L?psc=1&ref=ppx_pop_mob_b_asin_title ) and xlr cable to loxjie p20 tube amp. I hear absolutely no hum or hisses. I also have a Sennheiser gsx1000 connected to the p20 via 3.5mm to rca. Before i used the rca to xlr on the sp200, i used an rca cable from the m300 to the sp200 and it was full of hum and noise. Everytime I moved my mouse it would intensify. I also ordered the little bear m3 fully balanced passive switch box and intend to go with all xlr cables. But after reading that there is now real difference in SE and balanced inputs on the sp200, I may save $100 on the little bear and cables and just stick with the rca to xlr since it did solve the noise issue as well. I'm still a little confused about the dac sending out 4v through xlr and 2v through rca though. Am I still getting the full potential of the sp200 if it's only receiving 2v from the m300 dac?

 

[Veri]

I'm using a SMSL m300 connected to the sp200 via rca to xlr cable ( https://www.amazon.com/gp/aw/d/B077YL2J8L?psc=1&ref=ppx_pop_mob_b_asin_title ) and xlr cable to loxjie p20 tube amp. I hear absolutely no hum or hisses. I also have a Sennheiser gsx1000 connected to the p20 via 3.5mm to rca. Before i used the rca to xlr on the sp200, i used an rca cable from the m300 to the sp200 and it was full of hum and noise. Everytime I moved my mouse it would intensify. I also ordered the little bear m3 fully balanced passive switch box and intend to go with all xlr cables. But after reading that there is now real difference in SE and balanced inputs on the sp200, I may save $100 on the little bear and cables and just stick with the rca to xlr since it did solve the noise issue as well. I'm still a little confused about the dac sending out 4v through xlr and 2v through rca though. Am I still getting the full potential of the sp200 if it's only receiving 2v from the m300 dac?

4V input will be capable of higher maximum volume but that's it. 2v is quite capable

 

[taylptrsn]

Just got my SP200 on amazon from "SHENZHENAUDIO" it seems I dont have any play with the potentiometer and I haven't noticed any channel imbalance, I will test further. I am using inefficient planars almost exclusively though.

Edit: No play in my potentiometer, but the volume still effectively doesnt change from 3-6 O' Clock on the dial.

 

[frogmeat69]

Heck, even with my D50s connected to the RCA inputs on this amp, in high gain it has plenty of power to make my HiFiMan HE6se cans play very loud on high gain, gotta try it hooked to my RME with XLRs soon.
This is one powerful, clean sounding little amp.

 

[mks]

4V input will be capable of higher maximum volume but that's it. 2v is quite capable

Yeah, I did notice a very slight decrease in volume. Certainly not enough to present a problem. You are right. It's more than capable. Thanks for putting any reservations I had about sound quality diminishing.

 

[taylptrsn]

28 pages here, probably this has been already said, but worth an update: reason for having the exact same output power when switching from unbalanced to balanced is that the amp itself is not fully balanced. There is an OPA1612 at the RCA inputs which takes care of both Left & Right unbalanced signals, and for the balanced XLR inputs there're 2 x OPA1612 that are converting the unblanced for feeding the OPA564.

Seems that @yummy already "discovered" this here, but also other ASRers found this info as well, although worth mentioning again Benchmark's thoughts about balanced headamps: https://benchmarkmedia.com/blogs/application_notes/audio-myth-balanced-headphone-outputs-are-better:

"Benchmark does not offer voltage-balanced headphone outputs on any of its products. The reason for this is that a voltage-balanced interface serves no useful purpose when driving headphones. The truth is that a conventional single-ended headphone drive is technically superior to a balanced drive. This paper explains why single-ended headphone amplifiers are inherently more transparent than balanced headphone amplifiers.
[...]
We do offer a 4-pin XLR connection on the HPA4 headphone amplifier, because this 4-pin connection offers lower contact resistance than a traditional 1/4" TRS connection. For performance reasons, this connector is not driven with a voltage-balanced signal. Instead, it provides isolated left and right ground returns that are individually connected to the ground reference points in the left and right amplifiers.
[...]
Please understand that Benchmark strongly encourages the use of balanced line-level interfaces between audio products. All of our products are equipped with fully-balanced XLR analog inputs and outputs. In these box-to-box line-level connections, a balanced interface can provide substantial performance improvements. Balanced line-level interfaces reject hum and noise while providing a higher voltage level. The higher signal levels can improve the SNR (signal to noise ratio) of the audio system".

I'm personally only 90% inclined about what Benchmark engineers says, but I'm sure they're right.

As a side note, THX 789 has two output buffers per channel, the same OPA564 operational amplifiers, but each one is used to amplify the "hot" signal from the balanced signal.

However, like Amir stated, SP200 has enough output power and it has an extremely low-noise, so as long as this headamp can accept balanced interconnects (it's hard to pass 10m long with RCA cables and not inject some of the noise), then the most important aspect of purchasing a balanced amplifier is already achieved.

Some photos I found today on apos website: https://apos.audio/products/smsl-sp200-thx-headphone-amp. Seems that @Veri found this website too, so I'll provide direct links from their CDN servers:

Should I get a balanced dac because benchmark said so