CDs: FLAC v ALAC (v Digital Download)

If there is any difference in playback quality it was claimed that it was in the different algorithms needed to decompress each. Either from:

• Noise generated by the CPU during decompression
• Different timings of decompression causing the buffer/clock circuits to behave differently

As a person who evaluates algorithms for a living, I’d say that IF this were true it would be very much something that would be implementation specific. There are several major variables at play. 

 I _think_ ALAC is a little better in terms of compression.  So long as your player supports both there is no reason to convert.