Ripping CD's - Bypassing Computer CD Player

Dts, Digital files can sound different in spite of being "bit perfect". The main and only reason for that is jitter - a variation in time that converts into noise. Jitter creates sidebands that are at very low level but still very audible since not harmonically related to the signal. Jitter is a main problem of digital playback. It can be generated by the source, digital cable or the DAC itself. It is pretty much system dependent.

Kijanki - I assume bit perfect software/hardware delivery is a given. I am talking about different sound from bit identical files. There is no timing information in a digital file so the jitter comes on playback. There are lots of sources of it, as you say. But, how do you get different jitter from 2 identical files played back on the same system? It is theoretically possible, for example, if one file is contiguous and the other is badly fragmented and you computer and disk drive are really noisy. But if two bit identical files are contiguous and on the same platter on the same drive, some people will still say they sound different. That is the part I just cannot hear. Can you?

Let's not take this thread down the road of debating all those issues, unless the OP wants to. There are certainly endless threads on that topic I just wanted to explain to him some of the issues that are so often debated.

Kijanki - I assume bit perfect software/hardware delivery is a given. I am talking about different sound from bit identical files. There is no timing information in a digital file so the jitter comes on playback. There are lots of sources of it, as you say. But, how do you get different jitter from 2 identical files played back on the same system? It is theoretically possible, for example, if one file is contiguous and the other is badly fragmented and you computer and disk drive are really noisy. But if two bit identical files are contiguous and on the same platter on the same drive, some people will still say they sound different. That is the part I just cannot hear. Can you?

Are you talking about identical same format files (flac vs flac) or different format (flac vs wav)?

If same format, they should sound the same. Different format, then probably sound different since they are encoded differently even though both are lossless and uncompressed ... different file layout.

Some people claim that 2 bit for bit identical wav files will sound different if one was ripped directly to wav and the other ripped to flac and converted to wav. Same if a wav file is converted to flac and back to wav. Makes no sense to me, but some people claim they sound different.

Comparing flac to wav, some people claim the wav sounds better because the flac has to be decompressed and the extra CPU cycles needed to do that produce electrical noise that degrades the quality of converter or DAC conntected to the USB. On my system, the cpu runs at well less than 5% while decoding flac. Hard for me to understand how that changes a galvanically isolated DAC. I can understand that they will be a difference if the computer is controlling the timing. But in most cases today the external device is controlling the timing. The computer just needs to have a full buffer.

Different file layouts should not change the sound, unless you believe that the minute differences in how the CPU processes them causes a change in the connected equipment. The bits delivered to the buffer are identical for flac versus wav. Again, I am assuming the converter or DAC is controlling the timing.

Personally, I do not hear these differences. I just wanted to help the OP understand the issue.

There are also now devices on the market that try to completely isolate the USB signal lines and the ground from the PC. They also provide a separate 5V supply, independent of the computer. These devices may help if you have a particularly noisy PC or a poorly implemented DAC or converter. Some people swear by these devices, others ignore them.

Knghifi, I cannot hear the difference between different
formats or sources but it might be related to jitter
suppression in my DAC. Jitter might be related to amount of
electrical noise in the system making it difficult to
compare since this noise is changing. Radio stations have
to cut power at certain time, possibly at 6PM by FCC rule
(since propagation at night is much better). Testing one
file vs identical file before and after 6PM could result in
different sound.

Dtc, It is possible that decompressing or compressing file
that is being played somehow affects the timing but once
files played have the same checksum they have to sound the
same no matter how many times converted before. Badly
fragmented HD wouldn't change the timing since timing is not
attached yet (it is data) while HD is at least 1000x faster
than necessary to deliver this data (while data goes thru
buffers) but might possibly change amount of electrical
noise drive produces. It is far fetched but I've learned
not to question what other people can or cannot hear
especially when younger and/or musicians (trained ears).