Personally I would go the opposite way round, at least to get started.
The reason is that you'll need many adjustments, and adjusting the Expert filter settings requires a multi-step round trip with the configurator and the SD card. For dual mono it's even more effort.
Whereas you can jump out of your chair and adjust the sub upper rolloff directly.
In this setup described, where it seems unlikely you'll need to protect your wallmounteds from the deep bass that they can't fully reproduce, I'd run them filterless. I'd also run the sub from the Expert pre-out filterless - at least to begin with - and use the sub's upper roll off to remove mid-bass from the sub. Worth bearing in mind that every adjustment of upper roll off frequency will require a corresponding sub level adjustment (where one goes down the other up), and the best bass usually comes from a higher level setting and a lower crossover frequency than first expected. It's very unlikely the best crossover frequency will be 55Hz, for example, since so much depends on the order of the rolloff.
Personally I would start at the lowest possible crossover frequency, set the level correctly, and then identify any obvious gaps in the deep bass. If there are any, I'd increase the crossover frequency and lower the level, and test again for gaps.
I use a test tone generator and known mid/deep bass tracks which easily boom if not correctly adjusted to help get the crossover smooth. You'll know when it's right because the bass won't draw any attention to itself but will be thoroughly "there" and enhance the clarity and liquidity of everything above it.
Once you have the best crossover frequency for your speakers, room, and taste, it could then be transferred to a low pass filter on the Expert pre-out, or at least be a much better starting point for experimentation there. Beware the extensive choice of rolloff slopes which may/will be different to that in the sub. The frequency may well need to be changed for a different order of slope.
The reason is that you'll need many adjustments, and adjusting the Expert filter settings requires a multi-step round trip with the configurator and the SD card. For dual mono it's even more effort.
Whereas you can jump out of your chair and adjust the sub upper rolloff directly.
In this setup described, where it seems unlikely you'll need to protect your wallmounteds from the deep bass that they can't fully reproduce, I'd run them filterless. I'd also run the sub from the Expert pre-out filterless - at least to begin with - and use the sub's upper roll off to remove mid-bass from the sub. Worth bearing in mind that every adjustment of upper roll off frequency will require a corresponding sub level adjustment (where one goes down the other up), and the best bass usually comes from a higher level setting and a lower crossover frequency than first expected. It's very unlikely the best crossover frequency will be 55Hz, for example, since so much depends on the order of the rolloff.
Personally I would start at the lowest possible crossover frequency, set the level correctly, and then identify any obvious gaps in the deep bass. If there are any, I'd increase the crossover frequency and lower the level, and test again for gaps.
I use a test tone generator and known mid/deep bass tracks which easily boom if not correctly adjusted to help get the crossover smooth. You'll know when it's right because the bass won't draw any attention to itself but will be thoroughly "there" and enhance the clarity and liquidity of everything above it.
Once you have the best crossover frequency for your speakers, room, and taste, it could then be transferred to a low pass filter on the Expert pre-out, or at least be a much better starting point for experimentation there. Beware the extensive choice of rolloff slopes which may/will be different to that in the sub. The frequency may well need to be changed for a different order of slope.
1000 Pro / Magico A5 / REL Studio III
