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[dtc]

Compression can be done in a reversible way, so no information is lost. As an analogy, zip files compress computer files but can be decompressed to provide the exact original data.

As an example, if there are ten digital samples that are exactly the same (the same tone), then you can represent that as one value with a x10 to mean it is repeated 10 times. This saves space over repeating the same value 10 times. So, for example,

1245 1245 1245 1245 1245 1245 1245 1245 1245 1245

becomes

1245x10.

On playback, the compressed form is expanded to the original form.

Most people  compress the data. However, compressing and decompressing the data takes CPU cycles. So, there is usually a tradeoff between level of compression and amount of CPU to be used.  There are various levels of compression with FLAC, but the higher levels give very little extra compression at the cost of CPU cylces. So some mid level is commonly used.  The lowest level of FLAC compression may compresses  40%, but level 6 may only do 45%, with maybe 3 times the CPU needed to do the extra compression. Why take that much more time encoding for such a small gain in disk space?  Compressing takes time because the algorithm has to search for patterns. Decompressing is very quick and more or less independent of the level, since it is just interpreting the shorthand (like x10), not looking for patterns.

The 0 and 1 pattern of DSDs is not easy to compress, so it is normally just left uncompressed, although there are formats to compress it.

Hope that helps.

[Rossputin]

That helps a lot. So my overall question then remains: If FLAC is truly lossless, and if you optimize the compression level based on how much CPU you're willing to use, what's the benefit of WAV/DSD? Or am I mixing apples and oranges here somehow?

[dtc]

OK, some quick simplistic generalizations.

Some people believe that the small amount of CPU cycles spent decompressing the FLAC file is detrimental to the sound that is finally produced. This is through subtle factors of noise that get passed through from the PC to the audio system. Those people prefer wav or uncompressed FLAC. Others think this is hogwash.

DSD and PCM are very different digital formats and turning them back into analog uses significantly different methods, especially in the filtering stages. Those differences can produce different sounding music. It depends a lot on your equipment as to how much, if any,  difference you hear. Some people prefer DSD to PCM, some cannot hear the difference.

Both of these issues can get you into some involved discussions which can be as contentious as political or religious discussions. They are best avoided on this forum.

[Rossputin]

Thanks, DTC! That's super helpful and interesting. Actually makes me feel much better about FLAC.

As far as avoiding "Is DSD/PCM better?" it reminds me of a conversation I had with a friend who is a music critic when we were talking about Christmas movies. He said: "If you think online verbal fights about politics are brutal, you should see what happens when you take one side or another on the question of whether Die Hard is a Christmas movie!"

Now I'm going to listen to some Alan Parsons Project -- in both FLAC and DSD, but not at the same time 

[TheShoe]

OK, I know I'm getting into a slightly different topic than my original DSD question, but one last one: Re FLAC, how can a file be compressed and still lossless, and if it can be then why isn't more compression better (to save disk space, as long as it's still lossless)? Or is "lossless" really a misnomer? And if so, what does it mean with FLAC files (which is the form that most of my music is in)?

compression used for flac, as with zip files (for example) are definitely lossless as is ALAC and other audio formats.   they use various algorithms to compress the data which you can research starting here: https://en.m.wikipedia.org/wiki/FLAC

flac and zip use different algorithms to compress source material with flac taking advantage of the properties of audio (see above link). 

if you need to prove to yourself it is lossless, take a wav file and calculate an md5 checksum or sha1 hash.   convert it to flac.   convert the flac back to wav.   recalculate the md5 or sha1 and you sill have the same values indicating the conversion to flac and back to wav does not throw away any data.

[Awesome Donkey]

There is no audio data loss when using a compressed lossless format like FLAC or ALAC. The benefit for using a compressed lossless format is saving some hard drive space versus uncompressed FLAC or WAV. If you have a lot of hard drive space and don't care about file sizes, using uncompressed FLAC or WAV might work best for you. In that case I'd recommend using uncompressed FLAC since it has better ID3 metadata support over WAV.

[High-End]

just to ad another thing if one has still DoP problems with MC and a XMOS based SLSM DAC.

Perhaps a usb "cleaner" installed within the usb path?
I did and searched a couple of hours why the hell MC didn't recordnice the complete capabilities of my new SMSL DAC....
After unpluged the usb cleaner everything was fine ;-)