Have you tried to get those white socks look new white again. I have the answer for your problem. I use this method every other washing of my white cloths. You will see the difference by following the steps below.
Go to the your local store and purchase a bottle of Liquid Murphys Oil Soap.
Step2
Collect all of your not so white clothing (Example: Socks, underclothing)
Step3
Place clothes into sink, pan, bathtub, etc. Run warm water into the container. Pull 1 cup of Murphys Oil Soap into water and mix together. Let soak for about an hour(depending on how much whiter you need)
Step4
Remove the clothes and place in washer and add your detergent and wash as normal.
Tips & Warnings
You will notice that the whites are whiter and by washing them in your detergent the aroma of Murphys Oil Soap is not present after washing.
Do not use if you are allergic to any ingredients in the Murphys Oil Soap.