Two good amps done right are better than one. Especially when bass is offloaded to one designed to do the job and enabling the other to shine even brighter.
Of course one amp can do pretty well also but flat extended bass at high volumes requires gobs more power than the same down to only 40-50 hz or so, especially with less efficient speakers An amp overdriven trying to produce lots of extended bass clips and distorts which negatively affects everything.
SO there you go.
The good news is that many recordings have little in them below 40-50hz or so which is easier on an amp but many also do.
Keep in mind power requirements increase exponentially with lower frequency. Not addressing that effectively one way or another is a common snafu on the road to the best possible sound.