Yamaha HS7 on MOTU M2 line outputs, not on speaker terminals
Yes. The HS7 is an active monitor, so it belongs on a line output, not on speaker terminals. Set the level on the monitor itself. No passive SPL applies.
Connect the Yamaha HS7 to a line output and leave speaker cable out of it. The amplifiers are already inside the cabinet.
Yamaha rates the HS7 as 95 W dynamic, split 60 W to the woofer and 35 W to the tweeter, with an input of −10 dBu into 10 kΩ. A maximum SPL is not on that sheet, so this page does not print one. Balanced outs on the MOTU M2 are the connection.
Turn the monitor's own level down until a normal mix is comfortable, then leave it. Set the interface output near unity and do the rest on that knob. There is no passive wattage to compare, and filling in a maximum SPL that the maker did not publish would only invent a number. Speaker cable and an external power amplifier do not belong in this chain.