Combining .ISO's or .NRG's of Audio CD's?

I have been an audible subscriber for about 6 months now, and I generally copy the files to .nrg with nero and then rip with dbPoweramp. If you have done this you know what a pain it is. Is there a way to combine all of the .nrg’s to one larger file and then rip that? The largest amount of time is spent in loading the files and then entering the metadata for each individual “CD” Nero will not (Unless I am missing something) let you rip to dvd image instead of cd image, which would pretty much eliminate the whole problem.
Any other solution would be appreciated, but as it stands, it seems like if I could combine everything into one image and then label it and rip it would be the easiest solution.