This is the maximum C-weighted SPL for a pair of KH120As (loudspeakers alone and loudspeakers+sub) that

Neumann specifies at 2,3m:

View attachment 177942
Based on the above, at 3m distance (

see this calculator) a pair of KH120A should be able to reach a maximum of ~94 dB(C) SPL peaks if used fullrange, or ~101 dB(C) SPL peaks when crossed over to a subwoofer.

So assuming a generous 20dB headroom (for high dynamic range content and possibly some room EQ), you should be OK as long as ~74 dB(C) SPL (KH120 fullrange) / ~81 dB(C) SPL (KH120A with sub) average level is acceptable to you.

It would be best if you have access to a C-weigthed SPL meter to measure your current average SPL, and then see if the above would be enough for you.

Please also note that this is a bit simplified calculation, you can also

see this diagram from Neumann if you want to do a more detailed analysis and calculations for specific frequency regions.

Hope this helps!