SMSL SP200, THX-789, HPA4: THX Battle Royale!

This is a product review of the SMSL SP200 THX AAA-888 Headphone Amp (amongst others), which is available for sale now on Apos.

This review is posted here in partnership with It was originally written and published by Sandu Vitalie of on Nov. 22, 2019.

As promised my 3-way comparison review between 3 THX-AAA headphone amps is ready and here are my findings.

HPA4 and SP200 were already reviewed around here, THX-789 is a loaner unit from a closer friend of mine, thank you Dan for making this possible. In this review I will be as objective as possible and will leave my personal opinion behind.


  • All of them were tested connected to Matrix Audio Element X that streamed music directly from Tidal or from an external SSD drive full of Hi-Res PCM and DSD content so that I could completely remove the USB connection from equation
  • All of them were connected to Element X only via XLR cables and I listened only with headphones on the XLR output since THX-789 is halving its power on the 1/4” headphone out.
  • All of them were connected to Plixir Elite BAC400 balanced passive power conditioner to extract the best out of them
  • All of them were left powered On for a night so I would listen to them warmed-up at their fullest potential
  • Before testing and comparing them, it was mandatory to volume match them all and for that I used a very sensitive microphone inside the MiniDSP E.A.R.S system and REW 5.1 software to generate a 300 Hz sine wave to volume match them all at 85 dB of volume!
  • High gain was tested with Hifiman Arya and low gain with FiiO FH7 IEMs, I again volume matched all of them for the low gain setting.

Before going deep into this comparison, I will just remind you that HPA4 and SP200 use two flagship THX-AAA-888 chips and Massdrop THX-789 is using dual THX-AAA-788 chips. However, HPA4 is having an internal power supply of 35 Watts and SP200 is using a 24 Watt PS, it is normal that HP4 will output a lot more power especially for harder loads like current-driven planars. More about those THX chips in the pictures bellow.

Ok everyone, let’s keep the ball rolling.

1. Roger Waters – Déjà Vu

HPA4: Sweet sounding, voice is really deep, very clear micro-details, air moves around extraordinarily easy, there is more air moving on the right as somebody is moving around the microphone. Smooth and musical sounding, soothing, deep sounding piano. Treble carries a pretty nice impact; I can feel the small imperfections of this recording. Glass smashing sounds a bit weird but very deep into the mix. Violin decays naturally and easily, sounds are going from left to right and vice versa in a really holographic way. Accompanying voices are like whispering behind me somehow, a really pleasant feeling.

THX-789: Guitar is clear is very defined, the clocks on the left are also very clear and outlined. The air moving on the right is also present and I hear somebody moving around there. Violins and guitars are smooth sounding and are decaying naturally. There is a slight drop in the impact department when drums kicked in. I still hear the imperfections of this track very easily; depth is also impressive. Glass smashing also sounds weird and fake somehow. Accompanying voices are sounding closer to me, didn’t expect that.

SP200: Guitar is again sweet and defined, the heart beat at the start of song is a bit more powerful, the air moving on the right is as clear and defined. All the imperfections are easily spotted, Roger voice is deep into the mix and seems really guttural. The drums have a stronger kick by a smidge compared to THX-789. Glass smashing sounds fake and weird. Violin is clear and smooth but not as deep sounding as on the previous 2 amps. Accompanying voices are felt on the right and left and not behind me as on HPA4 and soundstage is by a hair smaller compared to THX-789.

2. Vivaldi (MQA Master) – 2L Reference Recordings

HPA4: Voice is sweet, musical, it grabs my soul, rises very high in tonality and dynamics are soaring. Violins are all around me and I am between them all. I hear how people are touching their musical instruments and deep inhaling some air before singing. Sounds extremely holographic, alive, open wide to a point of being magical. Background is the blackest I’ve heard. Chorus is full of energy, so much information, so clear sounding and so alive. I love it

THX-789: Voice is sweet, high in dynamics and tonality, very present but by a hint sounds less involving and soul grabbing. All the sounds are again around me, including behind me. Chorus carries good impact and high energy. I hear again how people are inhaling air in their lungs. Soundstage size is spot on and flies far but not too far away. Background is black and free of any gremlins.

SP200: Voice goes high in dynamics, sounds alive and rich in tonality. Everything happens around me. Carries a bit more weight with every note compared to THX-789, seems a bit more powerful to me. Dynamics rose higher in an instant, 789 is a bit leaner by comparison. Background is clean but not the blackest of them all.

3. Infected Mushroom – Guitarmass

HPA4: So alive, so hard kicking and so full of energy. Instant rise in dynamics, impact and kick. Very groovy and very pleasing, my ears are having an orgasm right now and I started head-banging. The mix is just perfect, flawless and everything is perfectly positioned around me. Some sounds are like coming from weird angles and are not supposed to be there, an impressive play with the right and left channels that wakes up imagination. This is the best linear, outlined, deep and controlled bass I’ve listened to, it’s perfect, no complains.

THX-789: Alive, hard kicking carrying gobs of energy. Dynamics rose high but not as high, impact and kick is strong. Has a bit less power and that can be felt especially on tracks like this one. The mix is good, but there is a feeling that something is missing from being perfect. Sounds are closer to me and some of them are not so scary real. I am still headbanging and grinning and it works perfectly with electronica. Bass is linear, extended and controlled but doesn’t kick in an instant, like it pulls the brakes a bit. Background is as black and noiseless and everything is just super outlined and presented on a plate to me to dissect.

SP200: Alive, kicks a tad harder than 789, full of energy. Carries impressive dynamics with an impressive impact into my eardrums. Mix is holographic and everything comes from different angles. Background is not the blackest, this is where SP200 is losing a bit of terrain that it gained in the dynamics department. I’m headbanging obviously as it pumps this mix directly into my brain, imagination start playing with me, holographic and deep sounding as well.

4. R.A.T.M. – Killing In The Name

HPA4: Tom Morello I love you, jam it, slam it, shred that guitar harder, so much raw energy, it never gets old, my blood always gets nuts while listening to this. What can I say, I’m really into rock and all it’s sub genres but I especially love when multiple genres can be found in a single band and R.A.T.M. is a very good example of that. The raw mix between lots of drums, beats, jams, guitars and that groovy voice just moves me and lifts me up every time, HPA4 does this so impressively well and so easily, its like having the band in front of you, just for you. The rise in dynamics is immediate and instant and I like that all those notes are not mixed together in a huge muddy blob, but are actually clear, defined and super textured. Can anything else sound as engaging and impressive?

THX-789: The slam is clearly a bit weaker and dynamics dropped lower as well. Nonetheless, I am still tapping my feet and I found it very engaging sounding but just not quite my tempo. The mix again is not crowded but decompressed and it’s quite easy focusing on anything I want. Everything shrunk a bit and depth information is not quite there as well. Everything else as black background and detailed presentation is there is spades and I have very little complaints.

SP200: Slams harder, controls better the headphone drivers, pumps more energy with every drum kick and every guitar shred, my mood came back in full-force. I’m sorry to disappoint the THX-789 crowd but for this type of music I enjoy SP200 just a bit more with its energetic and hard kicking approach. Background became noisier but not by a lot, it’s still under control. The rise in dynamics and lightning quick transients are almost HPA4 level, but again not quite my tempo.

5. Gothart – Simera Maura / Ketri Ketri

Can I continue without listening to some high-quality Balkan folk? Of course, I can’t.

HPA4: From the first seconds it is impressive how deep the big tambour can sound; it moves a lot of air and goes impressively low in bass regions. Those low intensity notes are coming in waves hitting one after another, such an amazing feeling. The mix is impressive and it’s very close to my heart, all voices are sounding heavy, guttural and I feel the voice cords vibrating. Trumpets are sounding sweet, melodious and impressively clear and outlined. In the background there are few sounds that recording engineer probably never intended to record like small imperfections, I am hearing those loud and clear.

THX-789: I immediately felt how the overall presentation took a step forward, everything just happens closer to me, I can’t look at a bigger picture as easily. The overall presentation is a bit smoother sounding and actually for this type of music it works very well. Even the big tambour decays slower, it actually sounds this way in real life. Short version is that everything is closer to me, smoother and slower sounding.

SP200: Hard kicking tambour is back; air waves are back and everything picked up the pace and smoothness took a small hit. It is closer to me sounding as THX-789, but it is not too far away from HPA4, I’m actually quick shocked about this. The ultimate detail retrieval is great and I can dissect everything with ease, trumpets are deep and really pleasant. The overall presentation is jumpy, I almost want to start dancing around. I like this one too

6. Pink Martini – No Hay Problema (OST of About Last Night)

HPA4: I felt how I opened my windows to this track, it just breaths, so much air around every note, so much depth information and so outlined is everything. The mix which is engaging and relaxing in the same time is quite special. I like that every single note is not touching another one, I can listen to them individually or a as a whole. This song again plays with my imagination having sounds behind me and coming really from different angles. An amazing performance.

THX-789: Bass violin sounds amazingly deep and lingers just a bit more, every hit is a bit subdued and calmer somehow. It makes you relax a bit more, feels like smoking a cigar while enjoying a smoother interpretation. Air bubbles between all notes became a bit smaller in size and again everything is closer to me. Past 3:50 mark and my imagination starts going wild again with notes coming from all directions.

SP200: Bass violin is now bigger in size, more imposing sounding and going even deeper. I checked again and all three are volume matched. The drums kicks are harder sounding and are pushing forward more air. I have this weird feeling that the headphone drivers are now bigger in size because everything sounds a bit bigger and bolder. Past 3:50 mark and dynamics kicked-in in full force, piano is super weighty and deep sounding. In terms of energy delivery, I am quite shocked how close this one is to HPA4.

7. The HU – Wolf Totem

HPA4: Mongol warriors sounded scary real and provocative. While they are throat singing – I am looking inside their mouths and spotting vocal cords vibrating so vividly alive. Mandolin and horsehead fiddle are deep sounding, very present and are sometimes switching places. Very musical, soothing, it’s calming but also putting me on the alert, I am experiencing the calm before the storm. When everything explodes in dynamics the sounds are hitting me again from different angles, accompanying voices are sounding behind my ears on the left and right.

THX-789: Mandolin is smoother sounding and has a longer decay, the big drum carries lesser air mass. Mongol warriors are sounding closer to me and scarier in the same time. Horsehead fiddle is now inside and not outside my head. The kick is good and overall presentation is engaging is pretty good in terms of slam. Throat singing is not so fearless anymore, a bit of its energy is lost, vibration of the vocal cords is not as clear. Since everything is closer to me, I need to close my eyes to focus on other sounds around me, it’s not as easy dissecting tracks.

SP200: The big drum pushes a bit more air, closer to HPA4 in this regard. Mandolin is not as refined as the one on THX-789 and it is not as smooth sounding. A bit rough around the edges and loses in the refinement department. Mongol warriors sounded scarier and their voice carried more energy with their raw, fearless approach. Throat singing is better as I can hear a good amount of vibration. Soundstage again took a hit and I need extra effort focusing on everything that is happening around me. Overall, the energy is on a high level and this is an enjoyable moment.


This comparison was was much harder to do, since all 3 units excel at transparency, detail retrieval and transient response and I needed to re-listen multiple times majority of those songs. Being 100% focused for a very long time is tiresome so I took few coffee breaks but in the end I have formed a very clear picture for all 3 units.

My general conclusion is that:

Benchmark HPA4 sounds the most detailed, the fastest and hardest kicking, it has the perfect transient response and the blackest background of all three. It sounded the most linear and truest to the recording, it is just not there when you listen to it. It is also scarily holographic and wide sounding (if the track is recorded this way). It can be ruthless sometimes and smooth sounding as well. It has a bit more power on tap than the others, it dissipates more heat and it is warmer to the touch and as a result I hear a better diaphragm control and an instant rise in dynamics and an instant stop of the headphone driver. With faster paced music its spectral decay is just perfect and it always delivered an enjoyable musical performance.

Massdrop THX-789 sounded almost as detailed and as transparent as HPA4. The only area where I felt it loses - is the frequency response, especially in the sub-bass area. It just doesn’t go to Mariana Trench levels as HPA4 does and doesn’t rumble my head as much when it is needed. Overall, it is gentler and smother sounding by comparison. Its spectral decay is longer and musical notes will linger a bit more. You might like this kind of approach with jazz or classical music. The background I would say it is just a hint greyer and not as black. Transient response is good but not the best, it is the slower sounding unit compared to the rest. I felt that its power output is lower compared to the rest and as a result this is probably why I didn’t hear the fastest transients or the best diaphragm control. Soundstage size also took a small hit and everything just happens closer to me, it is a bit harder focusing on everything in a crowded track and the air bubbles are smaller in size. All in all, this is a very good amp, it is pretty close to HPA4 once you volume match them, but still I would like to see few things improved in the future.

SMSL SP200: This little unit surprised me so many times already as it sounded almost as detailed as HPA4 and actually in terms of frequency response it surpasses the THX-789 because the sub-bass is better, goes lower and has a better sustain. It is not gentle or smoother sounding as THX-789 and sounds a bit raw and not that refined, but some music actually sounds better this way (electronica or rock is a good example). SP200 has an amazing slam, a lot of energy and carries a lot of air with every kick, it is very close to HPA4 in this regard. Its spectral decay is better, its transients are faster and as a result the diaphragm control is also better. It has just a tiny bit more power than THX-789 but in the same time the background is also greyer and not the blackest of today tests. Soundstage size is about on the same level with THX-789 and only sometimes I felt it smaller in size and cozier somehow. All in all, SP200 amazed me how energetic and punchy it can be and how close to HPA4 it can sound at only a small tiny fraction of its price. This one has the best value of them all and probably the best value of any desktop headphone amp as of right now.

If I would give a score to all of them, 0 being the worst and 100 being the best.

I. Background Noise / Distortion

1. Benchmark HPA4: 100

2. Massdrop THX-789: 94

3. SMSL SP200: 91

II. Detail Retrieval

1. Benchmark HPA4: 100

2. Massdrop THX-789: 94

3. SMSL SP200: 95

III. Frequency Response

1. Benchmark HPA4: 100

2. Massdrop THX-789: 92

3. SMSL SP200: 94

IV. Linearity

1. Benchmark HPA4: 100

2. Massdrop THX-789: 93

3. SMSL SP200: 95

V. Soundstage Size

1. Benchmark HPA4: 96

2. Massdrop THX-789: 92

3. SMSL SP200: 91

VI. Depth / Holography

1. Benchmark HPA4: 100

2. Massdrop THX-789: 94

3. SMSL SP200: 93

VII. Transient Response / Dynamics

1. Benchmark HPA4: 100

2. Massdrop THX-789: 92

3. SMSL SP200: 95

VIII. Power Output

1. Benchmark HPA4: 96

2. Massdrop THX-789: 92

3. SMSL SP200: 93

IX. Total Points & Overall Score

1. Benchmark HPA4: 792 Points (Overall Score of 99)

2. Massdrop THX-789: 743 Points (Overall Score of 92.8)

3. SMSL SP200: 747 Points (Overall Score of 93.4)