Lotoo PAW S2

Review Date: 21 January 2022

PAW S2 serving Line-Out Mode


  • DAC Chip: AKM AK4377
  • PCM 32-Bit/384kHz
  • DSD up to DSD128 Native
  • 4x MQA decoding.
  • THD+N: -109dB(0.0003%).
  • SNR: 123dB.
  • Max Output: 150mW per channel (4.4mm), 125mW per channel (3.5mm)
  • Frequency Response range: 20Hz-20kHz
  • Line-Out Level(3.5mm): 2.34 Vrms
  • Line-Out Level(4.4mm): 2.55 Vrms
  • Noise Level(3.5mm): -121dB
  • Noise Level(4.4mm): -119dB


  • FOSTEX T40RP MK3 (Magnetic Planar, 50 Ohm, 91db Sensitivity)
  • Beyerdynamic DT880 (Dynamic Drivers, 600 Ohm, 96db Sensitivity)


  • Etymotic ER4SR (Single BA, 45 Ohm, 96db Sensitivity)
  • TRN VX Pro (8 BA + 1DD Hybrid, 22 Ohm, 106db Sensitivity)
  • TIN HiFi T3+ (Single DD, 32 Ohm, 105db Sensitivity)
  • Shure KSE1500 (Single Electrostatic 200V, KSA1200 Energizer)


  • VE Asura 3.0 FE (Single DD, 155 Ohm)
  • VE ZEN 2.0 SLQ (Single DD, 320 Ohm)


  • Windows 10, Foobar 2000 (USB 3.0 Power)
  • LG V50 ThinQ (UAPP USB Exclusive Mode, Bitperfect)
  • Sony Xperia X Compact (UAPP USB Exclusive Mode, Bitperfect)
  • Tidal Masters (via UAPP)

Comparative Reference DAC/Amp:

  • iFi ZEN DAC V2 + ZEN CAN Stack (15.1 Vrms)


Lotoo PAW S2. A re-entry by Lotoo following up the success of PAW S1. Practically an upgraded S1, uses the very same DAC chip of AKM4377, but with better implementation and tuning. I can totally understand this move. Lotoo has chosen to work on something that they are already very familiar with – the learning curve from S1, the improvements all realized in S2. As such my impressions on this S2 will regularly touch on the subject of how does S2 fares against S1.

Build, Functions, Usability

Built like a Tank, S2 is one hell of impressive and elegant gadget. End to end, solid aluminum chassis to inspire good feel and heft when handled. With tactile buttons all placed with clinical precision for ease of reach and convenience.

There’s a Function button, Volume Up, Volume Down and a Pause button sandwiched in between. Practically emulating a micro DAP feature. Just like S1, a small LCD screen allowing for monitoring of relevant details and status. Usability of all these hardware features are realistic as it is minimal. From a Dongle perspective, this is already luxurious compared to many other options.

There’s Hi and Lo gain option for matching with the partners driving needs. Very usable gain elevation that really works as per intended. I always use Lo gain for my IEMs and Hi for my harder to drive stuffs.

PAW S2 included something called EFX. Basically presets of EQ for those wanting to play with sound alteration. However I never use EQ on any of my audio gears, so I didn’t test any of the presets. Leaving it to just set to None.

Then there’s a selector for Line-Out mode, something which is very unique to PAW S series after the update of FW Both S1 and S2 now with the ability to serve as AUX Line-Out (without the need for maxing the volume). I will delve more on this shortly.

Just like the S1, volume adjustment are done with two very tactile buttons that helps to regulate refined volume stages. Between jumps, it is calibrated appropriately allowing the user to fine tune the loudness in precise increments. The best way to use S2, just set the volume to 100% on the source transport and let it control everything.

Not forgetting the holster that has been designed for the convenience of latching the hefty S2 body with a clip. I have found this to be very useful while on the move. Normally I would latch the clip on the edge of my pocket preventing the S2 from dangling straight down.

MQA decoding, a rarity among AKM based Dongles, especially for an archaic chip like this one. Quite moderate at 4x unfolding, S2 actually performed amazingly well with Tidal Masters. Super smooth and refined without any hint of artifacts that resulted from less than competent MQA unfolding.

Endurance wise, the S2 scored respectable 6 hours of usage on my Sony Xperia X Compact (Android 8, 2700 mAH battery, Airplane Mode, UAPP with USB Exclusive Access, Bitperfect). Compared to competitors like Cayin RU6 and iBasso DC05, they all scored 6 hours under similar conditions, driving my TRN VX Pro (Lo Gain)

Sound Impressions

What is apparent, S2 retains the original implementation to sonic signature from S1. Which is already very analogue and organic smooth sounding. Absolutely free from any metallic or unsavory brightness as would be observed from many Dongles tuned inline with the current trend of projecting clean, crisp, bright and resolving sound. As I mentioned several times with my impressions, on some other Dongles especially ESS or Cirrus based models, some of them sounded unnaturally bright and digital – yes they are pristine clean and sparkly bright, but they also ended up sounding less realistic. PAW S2 is not one of those. PAW S2 is undoubtedly the smoothest sounding Dongle among over 100 units I have owned and tested so far. There are others as equally smooth, but the strength of S2 is its ability to retain good balance of crispness without being fuzzy.

S2 will greatly appeal to those appreciating their source being polished and articulate. There’s zero hint of dynamics aggression and vibrancy that falls into euphony elevation. S2 characteristics is the exact opposite of A&K PEE51 and iBasso DC04 (two of the most vibrant Dongles so far). However this also means there’s a caveat, S2 will not shine the best with an already warmer sounding partners. For example I have found that pairing S2 with TIN HiFi T3+ and VE ZEN 2.0 SLQ yielded something that is super smooth and lush, thus masking some of the resolution especially if the listener is the type that love to dig into precise imaging and details. Don’t get me wrong, there’s still details and solid imaging, however they are not as pronounced.

S2 shines the best with the likes of Beyerdynamic DT880, Etymotic ER4SR, TRN VX Pro, VE Asura 3.0FE and Shure KSE1500. Surprisingly, despite being the warmer type, my normally dark sounding Fostex T40RP MK3 synergize amazingly well too. Any element of listening fatigue non existent due to the smooth overall presentation. End to end dynamic range being projected with deft extensions. Harmoniously graceful and fluid all the way from Sub-Bass to Treble decays, rich and textured Mids. The general theme yet again smooth and organic. Despite being smooth, resolution, details and transparency still top notch, I don’t feel anything missing. One X factor that I believe the strength of S2, vocals presentation exhibited just the right level of intimacy especially for Mids centric partners – it does not add coloration, just that the projection is rich in density and textures. Treble being silky smooth with sensible amount of airy sparkle. Treble decays exhibiting equally fluid dispersal. Mid-Bass presence never attempting to overpower anything, it is amply commanding with fast attack and rumble, Sub-Bass focusing more on mature smoothness with mild seismic sensations.

What impresses me the most is how rich in density S2 is with note weights and dynamics composition. When I compared S2 with my desktop stack of iFi ZEN DAC V2 + ZEN Can (both being driven on USB 3.0 Power 5V 3.0A), that density alone was closely matched. About 90% if I am to put a number to it. That’s on par with Cayin RU6 performances.

Technically S2 delivers as per expected of a Dongle of this pedigree. Soundstage being wide as it is spacious with proper depth. Imaging clean with polished edges, not exactly clinical sharp as how it would be observed from the other top dogs, this due to the preference of lush smoothness in the overall presentation which some may even call as warm and thus imparting perceived “less than surgical precision”. But S2 is precise, it has the micro details and textures, it is just not splashed upfront. Spatial imaging well placed to instill holographic experience. Despite being a smooth operator, S2 is competently adept at speed and resolution. There was never a moment I am hearing any hint of strain handling complex passages or outright fast paced music, no instances where things gets muddy or compressed sounding.

Ultimately, S2 is very faithful to being a neutral source. Neutral and naturally organic, analogue sound that I dearly crave for being closer to realism.

Driving Power

Flanked by two juggernauts

As part of #donglemadness 2022 standard procedures, driving tests with two of my most difficult to drive Headphones. My desktop stack of iFi ZEN DAC V2 + ZEN Can (15.1 Vrms) used as a reference to ascertain how close S2 able to drive those two juggernauts. With the ZEN stacks providing 100% experience, this is how S2 compares:


  • Fostex T40RP MK3: 90% (Vol 78/100)
  • Beyerdynamic DT880 600 Ohm: 80% (Vol 80/100)

The percentage being indication of how close S2 to that iFi ZEN Stack. Of which the criteria for comparison as follows:

  • Listening loudness (proper level)
  • Dynamic transients and density
  • Headroom spacing and staging
  • Imaging strength
  • Details articulation

How close S2 to matching the output of the ZEN stack is nothing short of stellar. If I am not doing any critical A/B, I am perfectly satisfied with the quality of S2 on its own driving some of the most stubborn devices in my possession. This is the major difference between S1 and S2. The very same tests conducted on S1 and I demoted the S1 from 5 Stars segment because it fell short on power. S2 fixed that.

Additionally, I have spent quite a bit of time pitting S2 against other #donglemadness combatants. Including against the reigning champion and my personal No.1, CEntrance DACport HD. And here’s my findings:

Windows 10 64bit (USB 3.0 Power Delivery)
Sinne Eeg: We’ve Just Begun (FLAC 24/9.6 kHZ)
Diana Krall: The Look of Love (FLAC 24/9.6 kHZ)

Headphone 1: Fostex T40RP MK3 (91db, 50 Ohm, VE SDIC BAL Cable)
Headphone 2: Beyerdynamic DT880 (96db, 600 Ohm, VE SDIC BAL Cable)

iFi ZEN DAC V2 + ZEN Can (4.4mm BAL 15.1 Vrms, 3780mW combined)
Fostex T40RP MK3 Vol 40/100 Gain Stage 2 of 4
Beyerdynamic DT880 600 Ohm. Vol 35/100 Gain Stage 2 of 4

CEntrance DACport HD (3.5mm SE 4.1 Vrms, 775mW combined)
Vol 44/100 High Gain (T40RP MK3)
Vol 50/100 High Gain (DT880)

  • Performs 98% to ZEN Stack output, overall
  • Both exhibited similar analogue organic signature. Polished, crisp and smooth
  • Both equally great with macro and micro details
  • Both practically on par with technicalities

Creative SX-Fi Amp (3.5mm SE 2 Vrms, 370mW combined)
Vol 52/100 High Gain (T40RP MK3)
Vol 56/100 Adaptive Gain (DT880)

  • Performs 85% to ZEN Stack output
  • Similar analogue organic sound to ZEN Stack, just slightly less on smoothness, less air
  • A tiny bit less sharpness with imaging compared to DACport HD and ZEN Stack
  • Layers separation having less space in between compared to DACport HD & ZEN Stack
  • Marginally less width of headroom vs DACport HD and ZEN Stack

Lotoo PAW S2 (4.4mm BAL 2 Vrms, 150mW per channel)
Vol 78/100 High Gain (T40RP MK3)
Vol 80/100 High Gain (DT880)

  • Performs 90% to ZEN Stack output, overall
  • Smoothest analogue and organic unit among them all, yet still crisp
  • Very slightly Mids centric vs DACport HD & ZEN Stack
  • Milder edged imaging (but not fuzzy)
  • Staging and headroom width lesser than DACport HD & ZEN Stack

Last but not least, the burning question. How does S2 compares against Cayin RU6? no avoiding this as both of them are priced similarly and offers similar package in build and power delivery. I will make it simple. RU6 focuses more on being crisper and sparkier, while S2 emphasis is on matured smoothness. RU6 exhibited more pronounced attack and vibe, S2 chosen subtleties. Both equally amazing at being analogue sounding, a bit more organic for S2. Both equally competent at technicalities. The way I see it, owning both of them at the same time gives me options, options to suit my moods. It is not about which one better over the other simply because the sound presentation is different from some angles. Both are keepers.

Four way battle, S2 pitted against ZEN Stack, DACport HD & Creative SX-Fi Amp

Line-Out Features

What makes S2 unique from the rest, it is the only one capable of providing dedicated AUX Line-Out to external Amps and devices. For this purpose I have used my S2 as the DAC for pairing with VE RunAbout Plus 5 and Shure KSA1200 Electrostatic energizer. The entirety of my usage on 3.5mm SE (2.34 Vrms), which is more than enough. I can’t see how viable to use the 2.55 Vrms BAL unless of course perhaps if I want to feed it to a Power Amp for speakers.

With the RAP5, what I am getting is pretty much a full fledged desktop setup that is practically on par with ZEN Stack. What separates them being dynamics presentation unique to each devices. S2 retained that organic smoothness due to RAP5 being a very transparent Amp unit, dynamics signature retained with improvements on soundstage width and space. Markedly more air and sparkle too. In contrast, the ZEN Stack being crisper and with more vibrancy. Otherwise both being very enjoyable any which way I look at it.

However, I am disappointed with the pairing of S2 serving the role of AUX Lineout in this dedicated mode with my Shure KSE1500/KSA1200. Apparently the 2.34 Vrms feed exhibited audible distortions which the Shure Electrostatic energizer picked up. Even after tuning in a -10db padding the distortion is still there. I don’t exactly know why this is happening, but I have opted not to use the Line-Out mode on S2 with Shure KSE1500/KSA1200. It is a bummer but not a deal breaker. As I am still able to use S2 in normal mode where I can adjust the volume manually and feed it to KSA1200 energizer. All then performing flawlessly with the sort of quality I expected of the S2. I conclude that S2 will not be suitable for Amps that are exceedingly sensitive, fortunately this is a rare case. The majority of users don’t use sensitive Electrostatic energizers.

Shure KSA1200 energizer clearly picking up distortions with the red led


Lotoo PAW S2 is a specialty device. It does not attempt to be jack of all trades and has chosen a very specific sound presentation which has its own following. S2 is the smoothest sounding Dongle available now. Exceedingly mature, musical and polished dynamics with curated technicalities exhibiting moderation and fluid harmonics. Those preferring a more euphonic and bright sound signature will likely find S2 being less than ideal, especially if paired with warm sounding devices. But for those owning something like Etymotic ER4SR, Beyerdynamic DT series or anything that falls into neutral bright category will find S2 striking superb synergy. For my own usage I am most grateful for S2 ability in providing super smooth listening experience playing energetic, peaky and vibrant music, something like Rock/Black Metal/Indie. Equally enjoyable with Jazz for the lush and velvety experience without sacrificing resolution and technicalities. Not an easy thing to accomplish, so I give my two thumbs up to S2 for being what it is.


  • Highly analogue and organic timbre, polished and smooth
  • The smoothest sounding unit so far among 108 Dongles tested
  • Powerful dedicated AUX Line-Out mode
  • Great technicalities
  • Amazing build and features


  • The build is among one of the heavyweights
  • Less ideal for an already warm sounding partners
  • Line-Out dedicated mode not suitable for Electrostatic energizer


Best Pairing: Prefers listening devices that are natively bright

Back to #donglemadness

One response to “Lotoo PAW S2”

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s