Which ones? Almost all of them have at best 80 SINAD amps inside.
You shouldn't really compare the amp inside an active studio monitor to an external amp.
Most recent comparable ones I've heard are the Neumann KH80's. I'd be very surprised if the amps inside them are <= 80 SINAD, but I wouldn't be surprised if they aren't as good as the LA90 in terms of SINAD.
But again, not an apples to apples comparison.