Hi Looks a great forum. I have a bit of an odd question here.Hope someone can help. I have been burning some CDs that have talks lasting just under 80mins. Now the Cds state that they are 80minute audio cds( I think most CDs are the same these days). I have had no problem with them but it has been pointed out by a replication company i am using that the maximum Mb size on a CD is around the 650 mb size. Now the size of the file on some od the cds is around 810 mb. Could anyone let me know what the science is behind this and if i will have problems in the future with these large sizes? Up till now it looks like the cds are ok... thank you Paul PS The cd files are stereo. Someone has suggested i make them into a single mono file to reduce the size, but when i had a go it looks like the cd software creates a stereo file anyway so the size is back to 810Mb.Can a cd be burned with a single mono file? Would it play through just one channel ?