Alternative drivers for BK-12M suggestions…..????

Hello brains trust…!!!
Has anyone tried different drivers in a BK-12M enclosure..?? Apologies if this has been discussed before but every time I see a thread it derails into a sword fight…!!! Just looking for simple advice like; yeah I tried this driver and it was really good/crap.! Being driven by a Triode Lab el84 set/ffx in a small room 4.5x3.5.

I designed BK-12m as a simple, modified scoop-type bass horn for FE126En assuming it would be used on the end of a high output impedance amplifier (the E and En series assumed that as the usual operating condition). You can use the current NV unit as an alternative with a regular voltage source amplifier or something with a modest output impedance.