(12-16-2019, 04:59 PM)philrandal Wrote:(12-15-2019, 07:41 AM)rh2018 Wrote: Can Alsamixer card gain be set to persist through bootup by adding a command to a config file or start-up script?
As mentioned in Phil's post, The 4db attenuation when upsampling with SOX is important to minimise overmodulation.
The screen grab is from my Pi4 to HiFiBerry's new USB to I2S interface card and HiFiBerry Digi plus.
So far working very well with SoX set for 32/384 and Alsamixer at -4db as shown.
Richard
https://www.hifiberry.com/docs/data-shee...et-usbi2s/[url=https://www.hifiberry.com/docs/data-sheets/datasheet-usbi2s/][/url]
Do you actually notice the difference with the 4dB attenuation? And if so, what's the perceived effect? Just curious.
Phil
Phil,
It's a subjective thing but I perceive a slightly less congested sound on peaks in complex orchestral passages.
It's probably true to say that the peripheral equipment in the overall system will have more influence on the sound quality.
I don't necessarily think oversampling in SoX provides any real advantage. Depending on the DAC moOde might out put at 192k and even 96k with some earlier devices. The Pi4 in particular and I2S HAT's like Allo Boss and HiFiBerry DAC+ with separate clocks look after the Pi's shortcomings and moOde delivers the source bit-perfect.
In particular the Allo Boss can be configured in chip/device options for -6db gain and a range of filter characteristics. I normally apply the -6db option with the Allo Boss. In that case lowering the Alsamixer gain is un-necessary.
I'm not aware of any objective test for the PCM 51xx series for intersample or filter issues with program material but one has to start with the basic assumption that TI/Burr Brown, as well as other DAC manufacturers, set out to design state of the art chips. Their specifications speak for themselves.
Bottom line is I'll stick with the gain reduction and SoX disabled. I'm not using any other tweaks.
I'm using a power bank and that does make a difference! (Steps down from soap-box and takes dog for walk)
-Richard.
