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Massdrop 789 vs. Monoprice 887 vs. SMSL SP200: THX amp measurement comparison

RickSanchez

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#1
Due to the Green Bay Packers having a bye week (i.e., I have a little more free time than usual today) I thought it would be interesting to compare three high-performing and relatively budget THX headphone amplifiers: the Drop (Massdrop) THX AAA 789 vs. the Monoprice Monolith THX AAA 887 vs. the SMSL SP200 THX AAA 888. Thanks to @amirm for all of the measurements; all of this info is from him (unless otherwise noted), I'm simply putting the measurements side-by-side.

Unlike other comparisons I've written up this includes two samples for the SMSL SP200: a manufacturer-provided unit and a production unit.
  • All side-by-side measurements are shown with the manufactuer-provided unit. Additional measurements for the product unit are noted where applicable.


Author's notes:
  • Drop --> Monoprice --> SMSL is simply alphabetical; I'm not implying one is better than the other.
  • All of the graphics are labeled, but to make it consistent: Drop 789 is always on the left, Monoprice 887 in the middle, SMSL SP200 is always on the right.
  • I have no experience with any of these units, nor do I have any perspective on build quality / customer service.
  • If anyone sees errors / omissions please let me know and I will make corrections.
  • If anyone has issues with the measurements or conclusions ...... take it up with Amir! :D


References:

Shared Specs:
  • Inputs: balanced 3-pin XLR (x1), RCA (x1)
  • Outputs (headphone): SE 1/4 TRS (x1), balanced XLR 4-pin (x1)

Varied Specs:
  • Outputs (line): RCA (x1) pass-through on the Drop 789 and Monoprice 887 only
  • Outputs (headphone): SE 3.5mm TRS (x1) on the Drop 789 and Monoprice 887 only
  • Gain modes: x2 for the SMSL SP200 | x3 for the Drop 789 and Monoprice 887

Warranty:
  • Drop 789: 1 year
  • Monoprice 887: 3 year (replacement)
  • SMSL SP200: ? (If purchased via Apos there's a "2nd year warranty".)

Dimensions:
  • Drop 789: 21.0cm (W) x 22.0cm (D) x 5.7cm (H)
  • Monoprice 887: 22.1cm (W) x 19.8cm (D) x 5.1cm (H)
  • SMSL SP200: 16.0cm (W) x 14.9cm (D) x 7.3cm (H)




On to the amp measurements ........
  • You can click on each image to enlarge it.



SINAD

2.SINAD.png



SINAD for the SMSL SP200 production unit (down ~1 dB; the role of 2nd and 3rd harmonics has changed vs. the manf-provided unit):

2.SINAD_sp200_prod.png







SIGNAL to NOISE RATIO (50mv | 600 Ohm)
The Drop 789 chart didn't have the same mark-ups so it's shown here separately and not side-by-side.

Drop 789

3.SNR_a.png



Monoprice 887 & SMSL SP200


3.SNR_b.png



SNR for the SMSL SP200 production unit (~1.7 dB difference):

3.SNR_sp200_prod.png








Intermodulation Distortion (IMD)
*NOTE* The Drop THX 789 measurements are not shown separately, but you can see them in both charts as reference.

4.IMD.png






POWER VS. DISTORTION (300 Ohm load)

5.power_vs_distortion_300ohm.png


Power vs. distortion for the SMSL SP200 production unit (from Amir: "Performance is as identical as you can get."):

5.power_vs_distortion_300ohm_sp200_prod.png









POWER VS. DISTORTION (33 Ohm load)

6.power_vs_distortion_33ohm.png






POWER VS. DISTORTION (XLR out using 50 Ohm load)

7.power_vs_distortion_XLR_50ohm.png






FREQUENCY RESPONSE
*NOTE* I didn't find this for the SMSL SP200, so only the Drop and Monoprice amps are shown.

8.frequency_response.png





CHANNEL IMBALANCE

9.channel_imbalance.png


Channel imbalance for the SMSL SP200 production unit (from Amir: "This is quite different than the review sample. First, the level would not change for quite a while and once it started to change, it fell apart a lot sooner than the review unit. You can only get 30 dB of attenuation before channel balance becomes extreme relative to 70 dB before."):

9.channel_imbalance_sp200_prod.png







OUTPUT IMPEDANCE
*NOTE* I didn't see the graphic for the SMSL SP200, but I created my own graphic and listed it as 1.3 ohm based on this info.

10.output_impedance.png







CONCLUSIONS

Drop (Massdrop) THX AAA 789

From Amir:

"It takes a lot for someone like me who likes finding faults to smile ear to ear in testing audio gear. But that is exactly what THX and Massdrop have achieved. With a SIAND that matches the best dynamic range of our hearing system, you are assured that the only distortion you hear is either in the source or your headphones. Not only that, but we also have tons of power to drive any headphone at a price that is hard to believe for this level of performance.

So let me make this short: the Massdrop THX AAA 789 has my strongest recommendation. Buy one and be happy forever. :)"


Monoprice Monolith THX AAA 887

From Amir:

"I did not think it would be possible to build a mid-priced headphone amplifier and beat the Massdrop THX AAA 789. It is clear that the Monolith team managed to go against the tide and produce even a better headphone amplifier. Both subjectively and objectively, the "Monolith by Monoprice THX AAA Balanced Headphone Amplifier featuring THX AAA 887 Technology" (yes that is the official name) beats the Massdrop offering. Mind you, there is not much room left to squeeze one up there but they did. It is like beating the world record holder in Olympics.

Needless to say, it is my absolute pleasure to recommend the Monolith THX AAA Balanced headphone amplifier. It delighted me to see a company dedicated to absolute excellence and full transparency to our sources and content. This is a type of product you buy once and you are done. It made me happy just testing it!"

SMSL SP200 THX AAA 888

From Amir (manf-provided unit):

"THX seems to have revolutionized the mid to high-priced headphone amplifier market. It provides a winning combination of vanishingly low distortion and tons of power. Only JDS Labs has been able to keep up with it with Atom. We used to have one choice in THX amp which was drop.com and its notoriously poor availability. Now we are at the cusp of having two more options in the form of Monolith and SMSL SP200.

Great to see a new price point also in THX amps. You can add a $100 DAC to SP200 and still be cheaper than the other THX offerings.

Needless to say, it is my absolute pleasure to recommend the SMSL SP200. It makes THX headphone amplifiers more affordable and gets rid of clutter on your desk to boot.

NOTE: this is a new product. As with any new product, there may be delays in production, early teasing issues, etc. I can only vouch for the audio performance of the SP200. You need to do your own due diligence for other factor before purchasing."

From Amir (production unit):

"I see little evidence of SMSL having picked a special unit to send me. Performance is as superb as the review unit. Volume control has some issues but as mentioned, I think there are other explanations for this than a golden sample."


*Note*: There was no pink panther for the Drop 789, so I added what I assumed would be correct -- the golfing panther -- based on the measurements + Amir's statement ("So let me make this short: the Massdrop THX AAA 789 has my strongest recommendation. Buy one and be happy forever. :)") I'll edit if necessary.



11.conclusions.png



[edit 2019-11-17: added input/output specs and warranty info.]
[edit 2019-11-21: added measurements from production SMSL SP200 unit.]
 

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pozz

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#2

MediumRare

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#3
Could I ask a huge favor for you to compare the DX7 Pro headphone amp to any of the THX 887 so we can see what one might be giving up by going with a combo device?
 

RickSanchez

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#4
Don't forget the Benchmark HPA4 (THX AAA 888) & Monoprice Monolith THX AAA 788 Portable Headphone Amp & DAC. Although I would understand why these wouldn't be included given one's price and the other's portability.
Both great suggestions. But as you mentioned I wanted to try to compare pretty similar devices, so while I considered the Benchmark HPA4 I quickly realized that it was an order of magnitude more expensive than the 3 amps I included in this comparison.

I hadn't thought about the Monoprice 788 portable, but -- IMO -- it doesn't seem to be a good fit given that A) it's a portable, not a desktop device; and B) it's a DAC/amp combo and not just a straight headphone amp.
 

RickSanchez

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#5
Could I ask a huge favor for you to compare the DX7 Pro headphone amp to any of the THX 887 so we can see what one might be giving up by going with a combo device?
Obviously the time and effort I spend on comparisons is nowhere near what Amir does with his measurements and subsequent posts, nor are my comparisons as valuable. (They're basically just copy/paste.) That said, they take a fair amount of time. I'd actually suggest you just take a look at the headphone measurements for the DX7 Pro (they start about halfway down, with the SNR graph) and then compare them to the measurements for the THX 887. That should give you the info you need.
 
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#10
I don't really agree with using the SMSL SP200 measurements from the prototype Amir was sent. Would have made more sense to use the production model, which shows slightly worse distortion, harmonics and volume pot channel imbalance.
https://www.audiosciencereview.com/...200-do-we-get-golden-samples-for-review.9673/
Man I wish I would have read this prior to purchasing I was on the fence about this unit and a couple others and all the reviews I read were really good.....
 

Veri

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#11
Man I wish I would have read this prior to purchasing I was on the fence about this unit and a couple others and all the reviews I read were really good.....
Well I bought one myself. With anything but IEMs etc, there's no real problem. It's considerably cheaper than massdrop/monoprice one...
 

RickSanchez

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#12
I don't really agree with using the SMSL SP200 measurements from the prototype Amir was sent. Would have made more sense to use the production model, which shows slightly worse distortion, harmonics and volume pot channel imbalance.
https://www.audiosciencereview.com/...200-do-we-get-golden-samples-for-review.9673/
Fair point. I've updated the measurement comparison to include references to the SMSL SP200 production unit, where applicable.

FYI, as stated at the very top of my post: "If anyone sees errors / omissions please let me know and I will make corrections." In the future feel free to simply make suggestions for edits/additions instead of implying that the comparison is flawed; I'm happy to modify the initial post as necessary. Especially in this case, where Amir himself states that "For this assessment, I am just performing some spot checks as opposed to re-running all the tests." In order to make this comparison complete I had to use a number of measurements from the manufacturer-supplied unit provided in Amir's first set of tests. Thanks.
 
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#13
Well I bought one myself. With anything but IEMs etc, there's no real problem. It's considerably cheaper than massdrop/monoprice one...
i don’t use iems for home listening I’m Usually using my 6XX or 560II’s
 

Veri

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#17
I have the xdsd DAC/amp for on the go with some older Bose iems that are ok or my bluetooth Sennheiser iem true wireless momentum’s those are pretty great for on the go! I need a good pair of iems for on the go eventually!!
 
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#19
Hey, guys.

My first time posting here.

I need a bunch of small-but-great headphone amps for my recording studio & also my band, as we use IEM's (not wireless) on gigs. I'd love to go with the Monoprice, and I might, but I need six of them, so... ouch.

I'd love to save and get the SMSL, but there are several things that worry me. Most important is the output impedance. My Studio cans range from 250 to 600 ohms (Beyer DT770's) so no problem there, but the IEMS we all use are the Shure SE846, which are incredible, but sadly 9 ohms.

So of course I want the lowest output impedance possible.
The Monoprice specs say only 0.05 ohms for the single ended output. Nice. SMSL doesn't give thast spec, and ignores my email query, but an independent test says its output is 1.3 ohms. That's a HUGE difference. Couple thatn with only 2 gain settings instead of 3, and I'm a bit worried.

SO A QUESTION: The Drop and Monoprice units don't recommend using a 9 ohm source, anyway. Monoprice says 14 ohm minimum, unless you are very dareful with the output voltage. (And them what about the sound quality?) So maybe I'd be OK, with ANY of these amps, if I added a 32 ohm L-pad to the input of the IEMs?

What do you think? I assume that all of these units would still have ample power. Would this give me a solid frequency response & damping?
 
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#20
Another question about the SMSL vs the US -made THX amps:

Why has no one mentioned the power supplies? They appear to be radically different, and as we all know, the psu is a huge factor in how any piece of gear sounds.

I don't know what the maximum rails this circuit can run on, but more voltage swing is always desireable.
AFAIK, the best headphone amps all use 24v rails.

The Drop uses a 24v DC wallwart. Im assume it's a quality, regulated supply. (yes?)
The SMSL, however, uses a fully-internal psu, and it appears extremely small. Aditionally, it says +/- 18v right on it, although they claim the unit runs at 24v. My understanding of electronics gets a little hazy at this point, but I asked them to explain. Their response was:
"24W is the output. 18V is input. +/- 18V = 36v. 36v x 667mA = 24W."

Hmm. So does that make sense?
Do the US-made units also run on 18v rails?

Does any of this make anyone hesitant about the SMSL?
(If not, then great I can maybe save a lot of money.)

thanks.
 

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