Based on the picture in your profile, that's a good looking system! The distance of your speakers from the wall looks pretty good too.
A handful of things (you probably know many of these):
1. Is the base still muddy when you turn off the sub? If no, and assuming you don't have a high pass filter on your mains, the sub may be the culprit.
2. Is the base still muddy when you stick a sock in the speaker ports? Many speakers/subs come with foam inserts to tailor the sound of the bass region.
3. What feet are you using on the Monitor Audio Silver 6 and the sub? I placed Herbies Threaded Gliders under my speakers and some Hudson Hi-Fi feet under my sub, and those made a giant difference in cleaning up my muddy bass. Speaker/sub isolation is essential for me.
4. To hit the price point of ~$1000, the Monitor Audio Silver 6 make some compromises. The bass region may be one of those compromises, so an upgrade may be in order since you're looking for that next level up in quality.
A handful of things (you probably know many of these):
1. Is the base still muddy when you turn off the sub? If no, and assuming you don't have a high pass filter on your mains, the sub may be the culprit.
2. Is the base still muddy when you stick a sock in the speaker ports? Many speakers/subs come with foam inserts to tailor the sound of the bass region.
3. What feet are you using on the Monitor Audio Silver 6 and the sub? I placed Herbies Threaded Gliders under my speakers and some Hudson Hi-Fi feet under my sub, and those made a giant difference in cleaning up my muddy bass. Speaker/sub isolation is essential for me.
4. To hit the price point of ~$1000, the Monitor Audio Silver 6 make some compromises. The bass region may be one of those compromises, so an upgrade may be in order since you're looking for that next level up in quality.