Using dBpoweramp

It can be both but moStly imperfections in the CD that results in different results in multiple reads used to verify the data when there is no accuraterip data from prior rips by others available for reference. To get an accurate rip in that case, data is reread many times until similar results are produced more than once. That can take a long time depending on how many units on the CD are affected by imperfections. You can bypass the rereading that occurs and tell accurate rip to accept less perfect none validated data if desired in order to make things go faster, but there could be audible artifacts in the rip as a result.

Rocky, if a track you really want for whatever reason (for me often to just have all tracks in a release) you can set the bypass in the options after and just rerip the bad tracks to get the best results possible without prolonged rereads/waiting. If defects/bad reads are not extreme, there is a good chance the results will still be mostly good and still quite possibly not clearly audible if not perfect.

I know not perfect rubs many audiophiles the wrong way, but on the grand scale of things the sonic compromises that result may well turn out to be quite trivial compared to many of the compromises in good sound audiophiles sweat about frequently.

Another way to look at it is that CD defects have much less impact ripping with DBpoweramp compared to scratches or other defects on a vinyl LP. I've ripped thousands of CDs and can only cite one or two cases where the ripped files (often from CDs acquired used on the cheap) demonstrated audible defects upon playback. Not worth losing any sleep over.

If the CD is in such bad shape, and you gotta have absolute perfection, just buy a new copy in better condition.

If the prolonged re-rips are occurring regularly, on many CDs that appear to be in good shape even with no manufacturing defects, then it might be time for a new CD reader. As long as it is in good operating condition and of good quality capable of high speed reads, you are good to go. Most reputable CD readers used with any name brand home computer these days in good working order should fit the bill and need not cost a premium just for this application.

I use the default as well with FLAC to minimize disk space without any data loss and works fine.

I started out using .wav ripped using windows media player and converted those files to flac recently mainly to enable use with both Squeezebox and PLex systems and for the tagging/metadata benefits. If there is any sonic difference, I have not taken notice and believe both to be more or less equivalent in terms of information content and overall accuracy. dbpoweramp is more explicit about verifying accurate rips or not though.