Sean just a note to audio path. Bit depth change to 64 and back to 24 is because of Roon processing, same as gain adjustment. Check in the settings if you have any gain on (like track embedded gain, preamp gain etc). I don't use Roon, but in poweramp I have none of this, just resampling to 48 kHz.
I would not bother with bit depth 24 > 64 > 24 as its lose less (24 padded with zeros to 32 and then multiplied, reverse is reverse of this).
Gains not so but they are performed in 64 bit so also not a huge concern, but the biggest "Dudu" is that resample to 48kHz. While Roon or Poweramp will resample it pretty good (they have very good resamplers) it's not loseless. Other sources not so much as using crappy Android resampler optimised for speed and energy saving.
Regarding anything else, I agree. I bought it to replace a kenwood excellion with nexus carputer with bit perfect performance with DAC. This unit was hailed for audiophile quality, which should give me a red flag once pre-purchase enquiry about 44.1kHz out was never answered and later answered that it will be implemented.
I do get it, maybe it's not possible in current hardware combination, but then people think before designing.
I don't also agree with that condescending tone from Dudu and info that Bluetooth audio is analogue from module. So? Goes to AKM DSP. And surprise. AKM is switchable on the fly between all major sample rates! So sample it with 44.1 (if chosen system wide), have a separate pipeline for an output and all sorted. It won't be bit perfect but we'll avoid the worst of it - resampling music files which are usually 44.1kHz.
Somehow nVidia doesn't have a problem with no matter what sample rate - outputs as file is and... You have system sounds mixed in any sampling rate.
Will it be hard in the current hardware configuration? Possibly even impossible. But don't promise it just for sake of selling the product.
And don't answer like people have no idea, myself for instance I'm an electronic engineer with audio processing speciality. And I don't buy such answers.
Ps. I don't know what changed in recent Android versions but 5.0 could force Android mixer to work with 44.1 as base sampling rate by editing audio.prop file. Can't confirm with any newer as I don't have rooted android except 5.0. Sure, wasn't bit perfect but no resampling.
In Dudu it might be also easy but requires some work, sample BT with 44.1kHz (or any other system/user selected, could be dynamically set as depending on what file plays on music app), create a different audio receiver (don't use Speaker android output but one of the usb, user selectable) and we have audio out for DAC with all sources and no resampling. Spdif probably still will be 48kHz but heck, 44.1khz for DAC, sampled with 44.1 (or 96), with phone and navi.
@DUDU-HUANG dare to share magic behind Redpower 850 Crystal (Android) that outputs 44.1/48/96 kHz automatically depending on file sample rate? Must be a sorcery!
