Beginner's shopping list priorities

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21 hours ago, DonaldT2109 said:

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Does this mean that VLC, and other players, reconstitute the audio from FLAC file, adjust the original audio, change the audio back into PCM and send it to the DAC which (blindly) decodes PCM back into audio ?

 

I can not think of any other explanation and this would, therefore, make the player software the most critical part of the whole system by quite a margin

 

MY EDIT    or possibly VLC only ever decodes and then sends audio to PCs internal DAC for digitising and sending to  external DAC  viaUSB

 

No. Everything from digital audio file (FLAC, MP3, etc.) up to the final DA stage of the DAC takes place in the digital domain (obviously). If you are using USB, or SPDIF out of the PC, the built-in DAC of the PC is not used. VLC (the player software) does not convert to analogue and back to digital (PCM). VLC extracts FLAC, MP3, etc. to PCM. Tone control (DSP) is done directly in PCM, changing the digital PCM stream itself. Digital to analogue conversion *only* takes place in the (external) DAC after the USB, or SPDIF receiver circuitry, which clocks out digital samples to the DA conversion chip of the DAC.

 

I hope this helps.  

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7 hours ago, DonaldT2109 said:

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But I can't get my head around how a piece of software can, on the fly, after it has derived the PCM from the FLAC, then adjust analogue audio qualities in a digital file of zeros and ones in a 24-bit song with a 96kHz sample rate without setting fire to my processor. This is why I assumed that it decoded to audio, applied adjustments and re-digitized to PCM.

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PCM is just a sampled audio signal. A FFT algorithm can very efficiently calculate the frequency components that are present in the signal or in any small part of the signal (say 100ms). Digital tone control or equalization can then change the magnitude of arbitrary frequency components and an inverse FFT gives you the corresponding filtered sample values. All this takes place in the digital domain and can be done fast enough to not introduce unacceptable playback latency.

 

7 hours ago, DonaldT2109 said:

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I was hoping that VLC would have some sort of 'pass through' setting that says 'just derive PCM and then deliver it to the USB port, bit for bit exactly as you have read it'. I have spent a long time going through every VLC parameter and I can not find it, so I am assuming that if I set all Audio effects to 'OFF' then I will have  a bit for bit PCM bitstream sent to the DAC

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I don't think VLC has a setting for so called direct or exclusive (bit perfect) audio playback (WASAPI exclusive mode in Windows). As @Ajax said, there are many software players that do have this option such as Foobar2000 (Windows only), Audirvana, J River, etc. Also streaming services such as Tidal and Qobus have this capability. You have to select your DAC/driver in the player software and select exclusive mode or disable volume control (e.g. in Tidal).