So you're talking about the high-pass filter to the Thiels?
If so, my 1st response is 'why bother'? Using any of these filters introduces phase errors into the bass and midrange frequencies. Also, it sounds as if you're using one subwoof, so filtering the bass from the Thiels makes the low- and midbass mono instead of stereo.
My 2nd response is the less 'slope' (and phase errors) the better. If you feel you MUST use a hi-pass filter, use as gentle a one as you can select.
But try running them fullrange and filling just the bottom octave with the subwoof.
If so, my 1st response is 'why bother'? Using any of these filters introduces phase errors into the bass and midrange frequencies. Also, it sounds as if you're using one subwoof, so filtering the bass from the Thiels makes the low- and midbass mono instead of stereo.
My 2nd response is the less 'slope' (and phase errors) the better. If you feel you MUST use a hi-pass filter, use as gentle a one as you can select.
But try running them fullrange and filling just the bottom octave with the subwoof.