Hi,
in the world of ITB -6dB is all important, the reasons for are which thoroughly explained here:
Q for Paul Frindle
The thread is called 'Q for Paul Frindle'. There are some real heavy hitters here who know their stuff back to front, and in my opinion this thread should be made a sticky and compulsive reading for all those interested in crafting their ITB mixes!
Read it, word for word, and when you've finished, read it again!
Blessings and Love
Beya