Can iTunes now play play high definition music in high definition?

A record company is offering free downloads of high-definition music. I downloaded several music files encoded at 24 bit, 192 kHz ALAC. To my surprise, iTunes 12.0.1.26 on 10.10.1 Yosemite imported the track and played it successfully! And it lists that high-resolution information in the file information.

I had thought that iTunes could not play high definition files. I understood it to be limited to 16 bit, 44.1 kHz files. And so I had thought that special software is required to play anything higher than that.

So my question is: When iTunes is playing such files, is it actually playing them at full resolution, or is it down-converting them? (Or whatever the technical term would be for storing or playing the files at something less than full resolution.) I can't tell by ear because I don't have my computer hooked up to good speakers.