Hidizs S9 review
Left to right - FIIO BTR3K, SMSL Idea, Hidizs S9.
Build:
It's comparable in size to SMSL Idea, but it has Type-C USB port instead of Micro USB, and has a 2.5mm balanced port in addition to the 3.5mm single-ended port.
Unfortunately, there are no buttons at all - you have to control S9 using your OS/music player.
Sound quality:
Standalone, it sounds a bit colored, with a slight veil - not very transparent. Definitely justifies the "Velvel Sound" moniker.
It's not the typical warm coloration, like SMSL Idea/Sabaj DA2 - it doesn't sound warm, but there is some timbral shift.
This coloration is typical to the "home audio" AK products - 4490EQ and 4493EQ.
However, FIIO BTR3K (dual AK4377A) and Earstudio ES100 (dual AK4375A) both don't have this coloration, and sound perfectly transparent. FIIO BTR3 (single AK4376A) is somewhere in the middle coloration-wise.
Because of this coloration, vocals (especially female ones) sound a bit off.
Pairing with O2 (using S9 in DAC mode - at 100% volume), S9 sounds more transparent -less veil and coloration, tonality is much more natural.
Bass is very good standalone- full bodied with deep impact, almost perfect.
Surprisingly, the bass still improves when paired with O2.
Despite the improvements when paired with O2, it doesn't display synergy with Pro 82 v2, just a really good sound overall - no magical component here.
Comparisons:
SMSL Idea (DA2) standalone sounds better than S9+O2, more transparent and natural, the bass has more body.
FIIO BTR3K standalone sounds even better than Idea/DA2, and provides Bluetooth functionality.
S9 costs 109$, DA2 is available at 56$, and BTR3K is available at 66$ (
after the 4$ coupon in the first post).
I can see why some people may choose S9 over Idea/DA2 - addition of 2.5mm port, and a much higher single-ended output - 90mW vs 36mW into 32Ohm.
Compared to BTR3K, S9 looks bleak. Both have the 2.5mm port, and BTR3K has a much better sound coupled with a Bluetooth capability, including APTX-HD and LDAC. BTR3K also has a great app, which allows to customize its sound by choosing different digital filters and EQ. The only advantage S9 has is its power output - 90mW vs 25mW into 32Ohm single ended, and 125mW vs 78mW balanced.
Conclusion:
Frankly, I don't see a point to a 109$ tiny DAC/Amp without a battery and without a Bluetooth functionality.
Its form-factor seems to suggest usage with smartphones, but it will eat your phone's battery to provide that high output power.
And who exactly walks around with a DAC/Amp tied to their phone? Bluetooth is the only way to go with smartphones, LDAC provides 990kbps bandwidth - good enough for FLAC.
At 109$, there are better sounding and cheaper options - I can't recommend S9.
FIIO BTR3K at 66$ :
https://www.aliexpress.com/item/4000849710696.html (
use the coupon in the first post)
Sabaj DA2 at 56$ :
https://www.aliexpress.com/item/32825193760.html