Originally posted by Jgirardin
I have disabled the copy “on the fly” and I have recorded an audio cd on a maxel cd-r 80XL-S700Mb (and also a Tdk cd-R80) but the scratch noise is always present!
That’s not what I meant. You may have disabled “on-the-fly” in the program, but you did not follow my advice (grab CD on HD and listen to WAV files). So we still do not know, where the scratch noises come from.
Then I have used plextools (and also Exact audio Copy V095 prebeta 3) to extract .wave file and the audio files were perfect!!
Especially EAC (Exact Audio Copy) does what the name stands for. So the scratch noises result from not-so-good hardware or not-so-good software or a combination of those.
Finally, I have made some tests with nero cd speed but I don’t know how to interpret these!
Never mind, you finally know how to record perfect CDs 
Nothing seems to be bad. I have done the tests : transfer rate, Dae quality, access/seek time, cpu usage, burst rate, spin up/down, overburning.
But you did not find the “quality test”? Doesn’t matter, since it seems your hard-/software (when not using EAC or PlexTools) does not extract audio correctly. I suspect that already the WAV files on the HD are scratchy, so you would not find any quality problems on the CD anyway.
So the solution is quite simple: just use EAC or PlexTools.
I am a novice in cd writing so can you explain me what means “buffer-underrun”, please.
Should be in any FAQ: the cd-writer expects a continous data-stream. For some reason, your HD wasn’t able to transfer data at the requested speed, so the buffer in the cd-writer gets empty (that’s the “underrun”). Make sure your cd-writer runs with UDMA or DMA, not in PIO mode.
Kind regards Frederick