Yes! It's available now.
When WiiM Mini supports a bit-perfect function via digital optical output, it outputs the same bit depth and sample rate as your music source. I.e., if your source is 24 bit/192kHz, it will output 24/192. While if your source is 16-bit/48kHz, it outputs the same without up conversion. It uses the same sample rate/bit depth with your input source.
Of course, your downstream optical receiver (DAC or amplifier) needs to have the ability to handle the specified bit depth and sampling rate. To keep compatibility with the legacy optical audio receivers, we set the maximal output to 48 kHz/16-bit by default. You can adjust the output up to 192 kHz/24 bit from the WiiM Home App. It can be done by selecting the device tab > tap the device setting gear icon > Select audio settings > SPDIF output resolution. Then select your target sample rate and bit depth, play test audio to verify if your downstream receiver is able to receive it.
Check this article to find which sample rate/bit depth pair is supported for each streaming service.
You can listen to 192kHz/24-bit music from the following sources:
1. Qobuz with WiiM Home App
2. Amazon Music Ultra HD with WiiM Home App
3. Amazon Music Ultra HD casting from Amazon Music
4. Your music library from NAS server
5. Your music library on mobile device
You can listen to Hi-Res 24-bit/48kHz music from the TIDAL Connect or TIDAL in WiiM App for those TIDAL master contents (assuming you have TIDAL HiFi+ subscription).