Convert command loss image Quality (AI to PDF convertor)

Hi Friends,

While converting AI file to PDF/JPEG, I found that it loses quality of output file. I think I am missing some parameter with 'convert' command.

I am using the below command
convert.exe -density 288 +adjoin D:\Manish\ -density 288 D:\AA.pdf%02d.pdf -flatten D:\AAd.pdf

Please suggest me the parameters and its implementation to improve the image quality.