[Rinoue]

I have a bit perfect setup going on my computer and for the life of me I can't remember if I heard someone say it or read somewhere that if you adjust the equilizer on your foobar2000 that it won't be bit perfect anymore, is this true??

 

[KingStyles]

That is true. Anything done to the signal such as, replay gain, volume control,  upsampling causes the signal to be not bitperfect.If you like the sound equalized than go ahead and do it. Sometimes we get to caught up on "bitperfect" and dont do what sounds best for us. Just because you are getting bitperfect out dosent mean you are hearing the recording exactly as it should if your headphones have a u shaped sound signature. Equing the mids would help the recording be more accurate than it coming out bit perfect.

 

[Rinoue]

Thanks for the reply, and what you just stated opened my eyes, in fact I was so focused on this bit perfect deal I forgot about listening to the music the way I enjoyed it, and it's not like I have golden ears, I can't tell if a stream is bit perfect or not.
 
I will go ahead and equalize and enjoy my music and forget about being hell bent on it being bit perfect. Thanks!

 

[Ham Sandwich]

I try to have a setup that is capable of doing bit perfect through all of the digital steps.  Bit perfect from the music file, through the media player, through the audio drivers, and to the audio interface.  I want it to be capable of doing that bit perfect.  But when I listen I do things like enable a digital EQ or a software based crossfeed and at that point the bit perfectness ends.
 
Any processing that alters the bits in the media player is going to end the bit perfectness.  That includes EQ, digital volume adjustment, software based headphone crossfeed, resampling, dithering, and other software effects.  As long as I'm bit perfect up to that point I consider it good.
 
One case though where you want to be able to do bit perfect through from beginning to end is sending HDCD encoded music to a HDCD capable DAC.  If you rip a HDCD to lossless, send it bit perfect through your media player and bit perfect to a HDCD capable DAC the DAC will be able to detect and decode the HDCD.  If the bit perfectness is broken along the way the DAC won't see HDCD data and will play it as normal audio rather than HDCD decoded audio.

 

[Rinoue]

If that's the case then wouldn't Hardware EQ instead of Software EQ at the end of the chain after the DAC as processed it be good??

 

[Ham Sandwich]

Yes, a hardware EQ would have an advantage there.

 

[Hero Kid]

Why do I see some people saying that specific music playing software is or isn't bit perfect?
 
As I understand it, as long as the all the software does is open the file and play it, it should still be bit perfect regardless of what software is used?
For example, people say iTunes on Windows isn't bit perfect.

 

[Ham Sandwich]

It's not must the media player that needs to do the right thing and be able to play bit perfect, it is the entire digital path through the computer that needs to honor the bit perfect philosophy.  So the OS and the audio drivers also have to keep the bit perfect philosophy.
 
If the audio drivers have the sampling rate locked at 48 kHz and you want to play something with a sampling rate of 44.1 kHz you are not going to be able to get bit perfect output because the 44.1 kHz audio will need to be resampled to 48 kHz.  Audio drivers also like to be able to enable sound effects like EQ, bass boost, stereo widening, simulating a sub woofer, and things like that.  Many audio drivers have settings to do all that.
 
The OS also likes to be able to do resampling so it can mix audio from different sources. If you are playing background music in iTunes while also playing a Tetris game the OS wants to be able to mix the audio from both iTunes and the game.  When the OS mixes audio you lose bit perfect playback.
 
The OS and the audio drivers like to make it possible to mix audio so that multiple applications on the computer can all be making sounds at the same time.  The problems is that as audiophiles desiring optimal music playback we don't want the audio drivers and the OS to be doing that.  So we have to go to some extraordinary means to make sure our audio playback is not altered or messed with.
 
Some of those extraordinary means are things like using ASIO or WASAPI Exclusive Mode.  Both ASIO and WASAPI Exclusive Mode open the audio device in exclusive mode.  Exclusive mode means that only one application can use the audio device at a time.  No resampling or mixing or other funny business gets done unless the audio application wants it done.  The application playing the audio is in control of the sample rate and other playback settings and is now able to better guarantee bit perfect playback.
 
A problem with iTunes is that it doesn't offer any of those extraordinary means to better guarantee bit perfect playback.  The Windows version now has the ability to let you choose WASAPI Shared Mode if you are using a 32-bit version of Vista or Windows 7.  But shared mode is shared, it still allows other applications to share the audio device.  That means audio could get mixed and potentially resampled.  So you have the potential for bit perfect playback in Shared Mode if it is configured correctly and at the right sampling rate, but you cannot guarantee bit perfect playback beyond that.
 
The quest for bit perfect playback on a computer gets a little bit messy and gets into some geek level configuration knowledge.  Kind of messy.