PASS INT 3OA how loud does it play?

Hi,
I bought Int 30A and it seems to me that there is something wrong with it . First of all when I crank it to max level it still can’t drive my 4ohm ML Spires (91 db) loud enough and max reading that I can get on display is 63. I would expect that the max reading should be 100. Second when I compare its max output to the output of my XA 30.5 I get LKFS reading of 0.4 for INT30A while I get 1.4 reading for XA30.5 for n the same input signal. I suppose I drive 30.5 with pre that has higher gain but still I would not expect such a big difference. Any ideas?
Thank you,
Alex