What does Apple send to Apple Music Skill for Echo speakers?

When you stream Apple Music to Echos using the Apple Music Skill on Alexa, are the Echos getting Apple AAC and playing that? or, getting Apple Lossless and the internal Echo DAC is playing that?

Amazon says most Echos can play 16/44.1. Only Links and Studio do 24/192. But 16/44.1 on crappy Echo speakers is a step up, if that is what Apple is sending now.