Lotoo PAW S2

Design and under the hood.

The overall exterior dimensions of S2 are the same as S1, 66mm x 22mm x 13mm, and the weight is only 29.2g, up from S1 being 27.1g. Perhaps, 2g of extra weight is due to additional control button and some other internal changes. But regardless of the same dimensions, S2 feels slicker in comparison to S1 due to its rounded edges and more noticeable body curve. Its CNC aluminum chassis are referred to by Lotoo as having G3 Curve design with a 3D curved glass. While we are still dealing with OLED 2-line display, the display itself is bigger with easier to read font size.

In the heart of S2 you will still find high performance AKM4377 DAC, the same as in S1, and the same Blackfin DSP from ADI. Also, similar to PAW6000, they implemented AKM8142 PLL to clean up internal clock. The design supports playback of PCM 32kHz-384kHz, DSD64/128, and also MQA 4x certified. Furthermore, based on their own Lotoo OS (LTOS), S2 has multi-OS support and should work with iOS, Android, Windows, and even video game consoles such as Xbox, PS5, and Switch without a need to install additional drivers.

Similar to S1, S2 has 3.5mm single ended and 4.4mm balanced (Pentaconn brand name socket) headphone outputs and a separate opamp ckt, but the output power was boosted. S1 had 3.5mm 70mW and 4.4mm 120mW power rating, while S2 stepped it up to 3.5mm 125mW and 4.4mm 150mW. With higher output power, the current draw is a little higher too, in my measurements being 90mA (S2) vs 70mA (S1). And with both having 123dB SNR, the dynamic range is pretty good and the noise floor is ultra-low. Then, with the latest fw update (fw 2.0.0.4), Lotoo added Line Out (LO) functionality to both SE and BAL ports. When enabled, LO 3.5mm is 2.34Vrms and LO 4.4mm is 2.55Vrms, proper voltage level for use with external amplifiers.

From the exterior design perspective, as already mentioned, we are dealing with a slick curved CNC aluminum chassis that have OLED 3D curved display (128×32) on top, usb-c port at one end and 3.5mm (SE) and 4.4mm (BAL) ports at the other end. All the buttons are aligned along one edge with a FN button to access internal menu/settings, and volume +/- along with multi-function playback control button in between. The buttons have a nice tactile response, no rattling, feel solid. The multi-function remote control button works with single click to play/pause, double click to skip to the next song, and triple click to skip to the prev song.

I tested and verified on my Galaxy S9 the remote playback control with the following apps. All worked except for Tidal, and in some cases I had to make sure previous app is closed before I can control the new app without overlap:

  • HibyMusic – yes
  • Neutron – yes
  • YouTube – yes
  • Apple Music – yes
  • Spotify – yes
  • Qobuz – yes
  • Tidal – no (streaming Tidal Master shows OFS 4x)
  • UAPP – yes (streaming Tidal shows MQA. 4x) – better for Tidal

lotoo-s2-28

Once you power up S2 and display is on, you will see decoding file format along with sample rate, bit depth, gain, and volume setting across the top line and currently selected effect on the line below it. This way you can get an overview of everything in one clear shot. Pressing FN button once turns display on and off. When the display is on, pressing FN once more takes you to EFX menu where you can select among 5 EQ presets (classic, pop, rock, headphone, ACG-1) and 8 ATE presets (far field, near field, dental, cassette, vinyl LP, radio, game, movie). These are just presets, can’t be edited, and you can cycle though these by pressing +/- volume keys. Also, EFX can’t be used when playing MQA files. If you don’t want any effects, just keep cycling until you see “none”. You also have access to change the Gain between High and Low and to enable Line Out as you continue pressing FN button.

Page 3 – Sound analysis and Pair up.
Page 4 – Comparison and Conclusion.

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