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Testing Ground

Lotoo PAW S2 test: a portable mini DAC with customisable sound

By Alban Amouroux |

Lotoo PAW S2 test: Portable mini DACs have become commonplace in the world of music technology, partially due to the fact that their low price makes them widely accessible. The Lotoo PAW S2 is easy to use; simply connect it to a pair of headphones and your smartphone or DAP via the USB output. This device can definitely be classed as a premium product, offering integrated equalisation and a balanced headphone output.

The Lotoo brand is part of the Chinese Infomedia Group which develops professional products for all kinds of broadcasting. Infomedia equipment can be found in everything from radio stations to OB vans. The company has undeniable expertise in the field of sound which they soon began to direct into consumer audio.

It all began with their PAW-V professional portable recorder. They eventually dropped its recording ability to create the PAW Gold in 2017, a digital high-resolution portable audio player. The term PAW stands for Personal Audio Workstation. Though this original function gradually fell out of favour as time went on, the name stuck since it was already fairly well known within the industry. The PAW S2 we’re testing here is no longer even a portable DAP player; it’s a simple portable DAC designed to sustain the company’s reputation through the Lotoo brand, a well-known name amongst sound enthusiasts.

Specifications

● Portable DAC
● Price : 279 €
● High resolution audio: : 384 kHz/32 bits, DSD128, MQA
● Output level : 2.55Vrms / 2x150mW @ 32 ohms (balanced)
● Signal-to-noise ratio: : 123 dB
● Connectivity : 1x USB-C, 1x unbalanced headphone output 3.5 mm, 1x balanced output 4.4 mm
● Accessories : USB-C/USB-C cable, USB-C/lightning cable, belt clip
● Dimensions (l x h x d) : 66 x 22 x 13 mm
● Weight : 29.2g

Overview of the PAW S2

The PAW S2 portable DAC is small and light, and won’t disappoint those looking for quality without sacrificing portability. Weighing in at just over 29 grams, you’ll barely notice it’s in your pocket. The PAW S2 also fits snuggly inside the belt clip provided, which firmly holds the cable attached to prevent accidental disconnection.

The two-part chassis of the PAW S2 is made from aluminium. Two accessible screws allow access to the inner components (which are all miniature, of course). Inside are two printed circuit boards: one for digital, another for analogue. Between the two, there are some components that are covered and protected to avoid radiation. As such, the PAW S2 claims a noise floor of -121 dBu, i.e. absolute silence as far as our ears are concerned.

The sole input is a USB-C port that transmits both sound and power. There’s no battery in this type of portable DAC since it’s automatically powered by the USB link. The digital-to-analogue conversion is handled by an AKM4377 chip, which is mainly found in portable audio devices. This is combined with an AKM8142 chip for clocking and jitter elimination. This DAC supports audio files up to 32-bits and 384 kHz. Lotoo has also added support for the Hi-Res MQA file format.

The analogue board includes high-end, low-noise components such as metal film resistors. The amplification reaches 2x150mW at 32 ohms on the Pentaconn 4.4 mm balanced output and 125 mW on the 3.5 mm unbalanced output. This is combined with a low/high switch for adapting the output level to in-ear monitors or conventional headphones.

Using the PAW S2

The aluminium alloy chassis is finished in black paint. The slightly rounded corners make it easy to grip, plus they give the PAW S2 a premium look. The glass of the display screen is curved to match the shape of the chassis. The small screen displays information such as the gain level, volume level and DSP setting. It doesn’t display the song or the artist’s name, though that’s not necessarily important here. Instead, the display focuses on the DAC’s own functions.

The PAW S2 has four function buttons. There’s no on/off button as it’s automatically switched on when plugged into a smartphone, tablet or laptop via USB. Lotoo also provides two cables. The first is a small USB-C to USB-C cable (which is only 10 cm in length). This is principally for connecting an Android smartphone, allowing the two devices to fit side by side in your pocket. Directions for use are indicated on the connectors. The second 80 cm USB-C cable ends in a Lightning plug for apple devices.

The button that’s slightly separated from the other three controls the two functions specific to this DAC. The first concerns the high or low gain (depending on the type of headphones connected). The second function concerns the 13 applicable audio modes. They’re divided into two types of presets: equalisation modes (PMEQ II) and advanced DSP-type sound processing (ATE). These have been taken from Lotoo’s existing DAP audio players, with three new modes added specifically for the PAW S2. For EQ, you can choose between classic, pop, rock, headphone and ACG-1. As for DSP, the sound can be tuned to movie, game, radio, vinyl, cassette, near field or far field modes. As a result, it’s simple to customise your listening experience to suit your own preferences.

The other three buttons concern volume control and playback, with plus and minus controls surrounding a play/pause button. Oddly enough, it’s possible to control the playback status from your smartphone, but the volume can only be altered on the PAW S2. This means the smartphone’s volume buttons are inoperative on the DAC. We also found the placement of the plus/minus buttons a little illogical: they’d be more convenient if they were swapped around. Every time we wanted to turn the volume down, we’d accidentally turn it up, and vice versa. This is definitely a drawback.

Listening Experience

We connected the PAW S2 to a MacBook via USB-C and to an iPhone via Lightning. In both cases, the audio source was the Qobuz app which immediately recognised the Lotoo USB DAC as an available audio output. In terms of headphones, we were able to connect the device to both balanced and unbalanced models, though these can’t be used simultaneously as stated in the DAC’s manual.

First of all, the low gain setting is suitable for our Beyerdynamic headphones with an impedance of 250 ohms. However, the high setting doesn’t lend itself to low volume listening. We started off listening from flat, without any added processing. We’d save this for the end of the listening session, once we fully understood the capabilities of the PAW S2.

Stimulator Jones’ nu soul on his latest release, Round Spiritual Ring, proves that the PAW S2 provides a broad soundstage, offering height as well as width, all with a stunning depth of sound. The vocals stand apart from the instruments, delivering effortless readability.

Next, we moved on to Schubert’s Symphony No. 9 in C major conducted by Herbert Blomstedt. The orchestra took shape in front of us with good depth and layering. The strings and brass impose themselves without effort, and there’s an irrepressible dynamic rise that highlights the abilities and limitations of our trusty headphones.

The bass register is perhaps slightly lower, even when switched to high gain, than that of the reference wired headphone amps. For a portable DAC/amp, the PAW S2 performs quite well when listening to Darius’ OASIS album. The low frequencies are not exuberant but the sound is articulated with detail and fullness. This DAC has the ability to produce sounds that feel like they’re coming from somewhere outside of the headphone.

As for the EQ presets, rock mode emphasises the mid-high frequencies which is great for reproducing the sound of guitars. The ACG-1 mode is the heaviest, so that’s what you need if you’re wanting a bassy sound. ATE Radio mode is also pretty good, offering a good sense of compression. The other modes are more aesthetic than anything else… none of them can really claim to provide a more high-end listening experience; it’s just a question of personal preference.

Pros :
Rigourous sound signature
Broad soundstage
Adjustable settings and display
USB cables included

Cons :
Very short USB-C/USB-C cord
Volume can only be controlled from the DAC

Conclusion

The Lotoo PAW S2 portable amp/DAC is a versatile device. It knows how to faithfully reproduce music whilst making the most of the finer details to present the widest soundstage possible. The timbres are silky and never aggressive. The variety of different audio modes allows you to step far, far away from the faithful reproduction the device is capable of. They won’t be for everyone, but these modes definitely carry some merit since they offer you the chance to personalise your listening experience, even if they don’t necessarily improve the sound quality. In this sense, the PAW S2 is a bit like the Doctor Jekyll and Mister Hyde of mini portable USB DACs. We liked the accessories that were included (the two cables and the belt clip) and the informative display. However, the device is let down a little by the illogical placement of its volume buttons and the little click that’s audible in the headphones when playback is resumed. With its dual balanced/unbalanced output and gain selection, the PAW S2 should be able to accommodate all types of headphones. All these features make it a quality, compact portable DAC that would undoubtedly be a great addition to any audiophile’s arsenal.