Cd Ripping - is it better to use inbuilt CD drive of laptop or use an external Cd drive

I use iTunes with error correction turned on both internal and external drives. I only had trouble with 1 or 2 out of a one hundred CD. 

Unlike playing discs in real time the only thing that matters with drive is how fast it is i.e. How long rip will take.    The software used will determine quality of rip.   Internal versus external does not matter.  Whichever works best for you. 

Just like in real life for any laser reading process everything matters when ripping. At least if sound quality is an issue for you. You know the drill. Vibration related to the transport mechanism, static electric fields, seismic vibration, background scattered light, induced magnetic fields from transformer, etc, quality of power cord. The whole nine yards.

cheers

Get good program like EAC.  I use (free) XLD on the Mac.  Program can go to given sector multiple times until you'll get proper checksum (I set my XLD to 200 attempts max).  You are extracting data.  What is stored on your HD is data and not the music.
Difference between Itunes and better ripping programs is number of times it goes to the same sector before quitting and using interpolated data.  This difference would be bigger on badly scratched CDs and most likely inaudible on brand new.

I agree with the EAC suggestion made by several of the others. And at this point I see no reason to conclude that the USB cable had anything to do with the problem, in part of course because a different drive was being used for the two rips. (And see my paragraphs below for some additional possibilities).

Also, while this may not have any impact on sound quality, in my experience full size (5-1/4 inch) desktop CD/DVD drives tend to provide much more reliable performance over the long-term, especially when reading discs that are in marginal condition, than both laptop optical drives and the kind of small low-profile external optical drives that seem to be widely sold these days. If you are planning to rip a large CD collection you might consider purchasing a CD/DVD drive intended for internal use in a desktop computer, having a SATA interface, and putting it into a separately purchased 5-1/4 inch drive enclosure, that would provide a SATA interface internally and a USB interface externally. Online sellers of computer parts, such as Newegg.com here in the USA, sell many such things.

Or, alternatively, you may want to consider doing the rips with a desktop computer, assuming you have one, and subsequently transferring the files to the laptop via a flash drive or a USB hard drive or over your local network.

Also, if you are ripping to and playing back from the laptop’s internal "c" drive, and if that drive is a mechanical drive rather than an SSD, I would make sure that either Windows is set to defragment the drive periodically, or that you do so manually every once in a while. It is conceivable to me that sonic differences could occur between playback of two identical files as a result of differing levels of electrical noise (resulting in differences in jitter at the point of D/A conversion) if one file happens to be highly fragmented (broken up into different physical places on the drive) and the other is not.

Finally, in your comparison of playback of the two files, was the external optical drive either connected or disconnected in both cases? If it was connected in one case and disconnected in the other, I would not rule out the possibility of that being a contributor to the sonic differences you perceived. While that would seem to be unlikely, IMO it is probably no more unlikely than the possibility that the USB cable used for ripping was a contributor.

Good luck. Regards,
-- Al