Best smartphone to use as digital transport for USB DAC/AMP

Hello there, folks. I’ve bought a BTR5 to use as an external DAC/AMP with my main and only phone, which is Huawei P30 hoping to get a bang-for-the-buck audio quality. Some of you may already see the problem here. As it turns out, if you go down this road sometimes it may turn out not to be as simple as shelling out on the best external audio device you’re able to afford. Thanks to the EMUI’s specifics, it’s aggressive and non-customizable resource management algorithms in particular (as well as some other quirks, including Huawei’s custom USB drivers and objectionable Dolby Atmos implementation), P30 turned out to be a suboptimal digital source to say the least. The BTR5 does work in USB mode, in fact, just not up to its full potential - for one, EMUI limits the amount of resources available to the software player (Neutron MP, UAPP) and It seems that I can’t get the digital signal to circumvent the DSP implemented in the system, also. I’ve tried all the tweaks available (both in the apps themselves and in the EMUI system settings) to tackle both of these issues but to little effect.

I can’t afford to change my main phone and I’ve come to realize that using my main device as an audio source has proved to be way more inconvenient than I could imagine. All things considered, I think the best option for me is to get an used smartphone to serve as a dedicated digital source for BTR5. As such, it has to meet three main requirements.

  1. It has to be able to work flawlessly as a digital source over USB (decent USB C realization on both hardware and software (drivers) level, no ridiculous built-in OS resource managers etc.) This seems to be a tricky one, because both the majority of the users and the manufacturers themselves don’t give a damn about this. The only source of information on this issue is personal experience of very few sophisticated audiophile users able to tell if there’s something wrong with the setup’s final output, apart from the obvious issues such as audio dropouts, instantly apparent noise and/or distortion etc. Afaik, all devices from Huawei, some devices from Samsung and some Xiaomi devices are problematic with USB DACs.

  2. It has to have a decently powerful CPU and a decent amount of RAM.

  3. It shouldn’t cost more than 200$ on the aftermarket.

At the moment I’m contemplating slightly outdated LG flagships (such as G6+), but I’m not entirely sure about them actually fitting the first requirement.

I’d be very grateful for any help. I’m greatly disappointment with what I’ve got, but I’d hate to make yet another mistake that will drain my financial resources completely for nothing and leave me fooled twice too.

UAPP is the only application that can bypass the Android audio system and other DSP eventually included in the os, because it uses a proprietary usb audio driver, so if you got it, just enable the UAPP included driver in the UAPP settings and you should be able to feed the btr5 bypassing any os DSP and the automatic resampling of android

Thank you for your reply! As I’ve said, I’ve tried both software players and with all tweaks available and, of course, all necessary options (including UAPP’s USB DAC mode + Bit Perfect output) too. Actually, Neutron MP has a custom USB audio driver too, as far as I’m aware. UAPP seems to be the default choice for most, though, but I’m afraid that It doesn’t suit because I need to use EQ correction and UAPP’s PEQ with only six filters is not enough. Apart from that, even via UAPP in (supposedly) correct configuration I have the same issues as with Neutron MP. After conducting thorough research, I’ve learned that at least some of those issues are device (at the very least - OS) specific. That, together with realization that using my only device as a digital transport is more inconvenient than I though it would be, are the reasons why I’m asking for advice on which smartphone to buy if I’m looking for optimal digital-transport-over-USB functionality.

I wasn’t aware about Neutron. What proplems are you experiencing about audio quality?
The problem with Android phones usually is that they use the Android audio system that resample everything to 48kHz/24bit after there are this others app that includes specifics drivers for avoid the problem, but change the phone with another android phone will not fix the problem because even if the interface of differents android phones look quite different the core system of all is always the same and the drivers of UAPP and Neutron will work in the same way

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How a usb-c port should work? Last time I’ve owned a OnePlus was the 3 a long time ago, I don’t know now about this possibility to install others drivers on the OnePlus but it sounds actually a little weird to me because in order to do that you have to recompile the kernel and flash it or flash the vendor partition with updated libraries in this case actually you are not changing the driver itself but how it works for semplify

So I don’t think you’re gonna solve the “problem”

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That’s why the comment got deleted. In the original cyanogenmod you could choose from multiple drivers… But I haen’t been into the rooting scene and a quick googlesearch revealed I was very wrong :frowning:

It seems to be a little more tightly woven together these days :stuck_out_tongue: The wild west of Android roms seems to be over

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I agree is always more difficult find ROM and unlock the phones, an option for you can be the pinephone a smartphone with Linux is around 150$, on one side you gain the freedom to do almost everything on the system side but on the other side I don’t how many apps there are because smartphone with Linux are a really new thing.

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I think you’re better of finding a good rom :stuck_out_tongue:
@ Jean-Paul_Petrosyan What about a DAP?

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I’ve read a lot of complaints of Huawei phone’s users on their quirks/incompatibility with USB DACs since I’ve bought my BTR5. Also, I’ve read in few places that Huawei devices have some kind of proprietary audio drivers or something, which proves to be problematic. Sadly, I’d never though there could be such problems beforehand. This is from the UAPP’s developers forum: “Many Huawei devices for example hold on to their own USB audio driver and do not free/release the USB device for use with other apps like ours.”
Also, It concerns me that I do experience changes in sound from changing various options in software players which, in theory, should have nothing to do with the sound quality. Some of those (for example, Frequency Analyzer parameters in Neutron MP) may be linked to the amount of processing power available for the DSP that’s going on (EQ, Fader). Others have gotten me at a complete loss (Playback Mode - i.e. one track and stop (this one is optimal)/one track and next/one playlist and repeat etc). The Hardware Latency in the Neutron MP settings also has an effect on the sound.
Moreover, I have to close as much background processes (Apps and services) as possible to get best quality (again, may be due to the use of DSP which requires processing power) and turn off various EMUI’s visual and sound effects. It makes a noticeable difference, but it’s very inconvenient to do this every time I want to listen to music (and turn some of the features back on after I’ve done listening). Also, the EMUI’s built-in resource optimization service causes problems by limiting the amount of resources available for use at any given time. It also kills various second party apps’s background services and such. Sometimes, notifications don’t work properly. Sometimes, the apps are cleared from RAM even though there’s A LOT of it still available. This makes 2019’s sub-flagship phone behave like a very budget one in use (way too limited “multitasking”, aggressive CPU/GPU throttling, background processes not working properly).

I’ve thought about DAPs, but I’m afraid I can’t even afford one that would be on par with BTR5 in terms of “raw” sound quality. Moreover, I can’t do without some pretty sophisticated EQ correction and most DAPs have a very limited EQ functionality. There are some Android-based DAPs, but those cost too much for me (>400$) and also have very poor “non-audio” hardware (SoC, RAM). I’d be ready to deal with a “slow” UI, but thanks to my experience with P30, I’ve got an impression that I need decent amount of processing power for quality DSP.

If really there is a service that limit the apps resources, a way to fix it is:

Enable the developer options
(Usually tapping 7 times on “build number” in “about phone”)
In developer options open “running services” find the service and kill it

Repeat every time you turn on the phone

This at least should fix the resources management issue if the service is listed in the services list.

Well you weren’t using the phone for it’s ‘raw’ sound quality.
I wasn’t sugesting a DAP toe replace the BTR5 but the phone. You can still pair the DAP up to the BTR5 and I assume it wouldn’t have weird USB-issues since it’s made to play audio? Just a thought

Sadly, it’s not that simple. Previously it could only be disabled via ADB command, but it seems that in newer EMUI versions this backdoor was “fixed” by Huawei. Here’s relevant topic on the XDA-developers forum:

This guide is for remove the app, my procedure just disble the service without remove it, maybe you can still do that.

Oh, now I get it, sorry for the misunderstanding. Actually, afaik not just any DAP has digital source functionality - some can only act as external USB DAC themselves. Some of them can and are being used by people as digital transports for their USB DAC/Amp, though, but there’s still an issue with lack of proper Parametric EQ.
All things considered, I feel like the best option for me is to get a ROOT-able few-years-old flagship smartphone on the aftermarket that will have minimal amount of relevant issues which can’t be fixed by the end user.

No, sadly you can’t do that. That’s actually the reason people get so desperate as to go through the ADB method. I’ve tried going the road you mentioned before - the option to force close/kill the service is just inactive.

Yesterday I’ve tested BTR5 in wireless mode via Neutrons Generic Driver > Hi-Res Bluetooth output. Funny enough, the sound was a lot more similar to what I get when connecting BTR5 in USB DAC mode to my PC, listening through Foobar2000 via WASAPI driver output (ASIO is a no-go as I’m using Peace APO which doesn’t support it). Yep, it’s seems like my Huawei indeed has issues with external USB audio devices.