Has anyone have experience connecting REL subs to Mola Mola Perca amps, class D

Hi,

I have a pair of Mola Mola Perca amps. These are Class D amps and are stereo amps. I use them in a vertical Bi-amp mode.

I am thinking of getting a pair of subs, likely REL subs (Carbon Special or Classic 99).

I am concern about connecting the REL subs via their high level speakon inputs to the speaker terminals of the Mola Mola Perca amps as these are Class D. The REL literature says to either connect the black ground wire to the amp chassis or leave it floating. Does anyone here have experience with RELs and the Perca amps please.