I have tried different official and custom firmwares, none allow passthroug.
I bought it as an audio player, using the optical output with an SMSL Sanscrit Mini DAC connected to a high-end tube amplifier and a pair of original Pro-Ac Response 2.5 the sound is really very good.
But you always think of improving a bit and a week ago I replaced the DAC with a model from the same manufacturer, SMSL, this time the Sanskrit 10th MKII, with a display and much more capacity in terms of sampling rate, 32kHz ~ 192kHz, data bits. 1bit ~ 32bit, DSD64 ~ DSD512.
My surprise has been to find that regardless of the file it plays it always plays at 44kHz, it doesn't matter whether it is 41kHz or 768kHz the DAC always works at 44kHz.
I have tried with the following firmwares:
Q10 PRO FIRMWARE 2.1.4. INSTALL ON ANDROID 7 v2.0.4 + ONLY. FUTEKO. HMD-2.1.4 2019-05-31-01
update_Q10Pro_HMD-2.1.7 2020-08-18.140128
update_Q10Pro_ (update & themed & Kodi18.2) [v1.1] -HMD-2.1.7 2020-08-18.140128 (from pcristi)
First without updating Kodi and after updating, choose the passthrough mode you choose, the result is always the same 44kHz.
I have tried different sources and it shows the sample rate correctly.
I think some thing are missing in the kernel.