Pls Help w/Redken Double Lights HairColor

My natural hair color is black level 2 w/VERY strong red undertones, and it is very hard to lift.  It usually takes a few hrs at the salon.   I would like to get my hair to a light ash brown.  My hairdresser just moved out of the area, but she gave me my formula before she left.  It was 9n with a drop of 6nb.  Although I liked the color, it was still too warm for me.  By reading another post, the coolest color combination is ag.   I just learned of the new Redken Double Lights for Level 1-5 hair.  Looks like the lightest shade is the 10ab, but there is no 9ag or 10ag.  I was thinking that the 10ab would work just as well at cutting out the red/orange/brassiness? If not, any suggestions on what would work better?

Also, after my hairdresser colors my hair we also have to use a toner to cut out the residual brassiness. But, she didn't tell me which toner she uses.  I looked at the Redken Shades EQ, and I am thinking that the 9n would cut out the most red/orange/brassiness.  Any help or suggestions would be greatly appreciated.  Thanks in Advance!