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Bit perfect / upsampling double-check


drftr
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Hi,

 

I'm buying the highly regarded Cayin RU6 DAC to catapult the sound quality of my phone into audiophile levels. To truly use its benefits it needs to avoid Android's upsampling and receive a bit perfect signal. AFAIK the most common apps that can deliver this for external DACs are UAPP and Neutron. But since I've been using Poweramp with so much pleasure over the past year I don't really want to give up on it. For that reason I want to do a last check:

 

Are there any upcoming plans to circumvent upsampling so that Poweramp can be used for more audiophile solutions?

 

Tnx...

 

drftr

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Most Android firmwares do not support bit-perfect audio transmission paths, and there are other considerations such as audio glitching during any transitions, issues with gapless and crossfading, etc. It would also mean blocking the use of the Android volume controls as they scale the output digitally rather than in the analogue domain, and thus changing volume would no longer be 'bit-perfect' (levels would have to stay at 100%, matching the content provided by the source).

I guess the only way to guarantee a digitally bit-perfect match between the source material and your ears would be to access the hardware directly using custom-written code for each model of external DAC, which is not something Max has indicated he wishes to do for a general market product. Have a search in the forums for the responses to other threads on this subject.

Also, what guarantee do you have that the source material has stayed at a single resolution and bit-depth throughout the studio recording and mastering stages? Most likely the mixing desk for example would be processing at different resolutions to the consumer output anyway.

Andre

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I'm simply sharing the thoughts of dozens and dozens on Head-Fi DAC forums that feel forced to move to UAPP to arrive at the sound quality they're looking for. If that's not a priority that's just fine and probably a good choice: It's in the mainstream one makes money. It's simply a pity that people who want to step up their game to high end quality can't ise the same app. But so be it. Our problem indeed.

 

drftr

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@drftr for USB-DACs Poweramp only uses Android provided USB layer/"driver", so while you can get Hi-Res sample rates/formats for it, it won't provide bit perfect solution, just due to the volume applied (not due to the resampling, which can be avoided if you use matching sample rate/format). 

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3 hours ago, maxmp said:

@drftr for USB-DACs Poweramp only uses Android provided USB layer/"driver", so while you can get Hi-Res sample rates/formats for it, it won't provide bit perfect solution, just due to the volume applied (not due to the resampling, which can be avoided if you use matching sample rate/format). 

But this requires changing the settings for each rate as the songs change, if the library had multiple hi-res rates. Note for most external DAC units, they the lass through an external amplifier down the line with a volume control. So in these cases, bit perfect should be possible eliminating the requirement for volume control.

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When using an external DAC and bit perfect it apparently is advisable to use max volume from the phone so that's what I do. From reading I take it a bit perfect signal degrades when not doing so. I call that a bit-less-perfect, but anyway. The things we do for love... 😉

 

drftr

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1 hour ago, drftr said:

When using an external DAC and bit perfect it apparently is advisable to use max volume from the phone. From reading I take it a bit perfect signal degrades when not doing so.

To be truly 'bit perfect' the signal that is received by the convertor which creates the analogue waveform for sending to your ears must be the exact same set of ones and zeros that left the studio engineer's mixing desk. Or as that's highly unlikely, at the very least the same ones and zeros that exist in the audio file that you have in your possession. That means no compression, manipulation, EQ adjustment, fading, balance, gain, level matching, or otherwise changing in any way the binary data. That would include adjusting the gain in the digital domain, which changes the numeric value of every single byte of data in the stream. So the only volume control should be a rotary knob in the final analogue power amplification box. And I'm personally not convinced that's very likely...

Of course, that's not to say that it wouldn't be a nice marketing claim to be able to directly pass-through an identical bitrate and sampling frequency as that used in each source file - assuming the output hardware fully supports it. Probably the audiophile equivalent of the emperor's new clothes given everything I said above, but it'd certainly look good on the spec sheet - not to mention preventing more threads like this one. :)

Andre

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2 hours ago, andrewilley said:

To be truly 'bit perfect' the signal that is received by the convertor which creates the analogue waveform for sending to your ears must be the exact same set of ones and zeros that left the studio engineer's mixing desk.
 

That means no compression, manipulation, EQ adjustment, fading, balance, gain, level matching, or otherwise changing in any way the binary data. That would include adjusting the gain in the digital domain, which changes the numeric value of every single byte of data in the stream. So the only volume control should be a rotary knob in the final analogue power amplification box.

Bit perfect means playing the file back exactly as-is. This is not the same thing as expecting something from the engineer or some other originating part of the recording process.

There are many, many systems that behave this way. A proper external DAC expects a digital signal from a source (in this case we are talking an Android device via Poweramp), decodes this signal to analog, and send that on to the preamp/amplifier/speakers, with only an analog volume knob in that chain. So yes this would benefit from a bit-perfect presentation to at least faithfully maintain the potential of the file format.

Regardless of any personal opinion, this is a very possible thing that an Android device can support. There are apps that do it (UAPP, Neutron) but so far not with Poweramp. But where those other apps fall short is the UI and library management that Poweramp does far better. So while it won’t benefit any users with traditional earbuds or using a phone’s built in speaker, it would certainly address an ongoing request for those with the equipment that can. I don’t think this is something that should be so summarily dismissed as a “marketing” claim.

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Posted (edited)

Thank you for not trying to defend Poweramp no matter what, and keeping an open mind instead. My gear is a couple of grand and I'm simply trying to keep the great UI and functionality of Poweramp without missing out on the ultimate sound quality. There's hundreds and hundreds of people like me looking for the best possible quality out of a portable setup and I was simply trying to point out the opportunity to become the top 1 app that has it all because that simply doesn't exist now. If that is not a desirable goal then so be it and I absolutely understand. But hiding behind invalid arguments doesn't help either case. It's best to make business decisions with eyes on facts, possibilities, business goals, and restrictions.

 

drftr

Edited by drftr
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  • 2 weeks later...

Im not so technically educated as you guys but I feel like we have the same request (drftr). I've been using Poweramp for years now. Then I bought a DX160 from Ibasso. Initially, I used their default player to test the overall experience then lately switched back to Poweramp.

1 thing i notice is the sample rate. I have songs that are 44.1khz, 48khz and some 96khz. The Ibasso default player was "auto switching" its sample rate depending on the track. But in Poweramp, you only got the option to choose (in my case) 44.1khz upto 192khz. Well im not that expert so I just chose the highest one thinking it will give me the best quality 🤣

Then I got to the point where I am using Poweramp and I played a track which is 48khz. And my Poweramp settings is set to 192 khz. I notice some type of "noise". Its like the "highs" got less clarity. So I tried switching the sampling to 48khz. The noise was gone and it is clearer. 

I hope I am in the right thread lol. Sorry my reply here is kinda long. Cheers!

Edited by VonAstorga
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