FIR filter format - Brutefir - Volumio
Yeah, I answered my own question.
So tried the same filter adding zeros to a total of 32 taps.
Plays great now and spectrum is better in the highs.
So this is the filter:

1, -0.15, 0.026, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
(Total taps: 32)