What you mean by bass extension? Bass on this speaker is totally fantastic. From 60Hz it is linear on FR. What else you need?The R Series towers already had poor bass extension despite it’s rigid and heavy cabinet and size. If an audible improvement js what should have aimed I guess, this would have been something which could have been improved. But I understand that would just make it dangerously close to the references!
You can't find better for that price.
Great measurements and great bass sound. They even keep bass driver.
If you need 40Hz buy reference or another speaker.
Answer specific not in common terms. Where is so called problem with bass extension?