.:suggestion:.
you mentioned that you've tried to use P2Ktools and found the gain table settings..try to increase all the fields by at least twice or thrice..then save/write it to your phone..reboot your phone and check if it made any difference..if it does then just play with the fields of the gain table until it suit your preference..there are labels in it anyways so you'll know what part of the gain table you are altering..
if after adjusting the gain table and saving it to your phone and rebooting your phone still nothing changes then it may be a hardware problem..
remember to back up your gain table before changing anything in it..
hope this helps..
