Maybe Iím missing something here but why not just use the CarPlay interface?
Most of my music library is apple lossless. I also have the kenwood 9905s. I have no issues with playback with my phone being the source of music through CarPlay.
This is exactly what I've been doing. Plugging the phone into the HU via usb and using CARPLAY. However, I confirmed with Crutchfield & Kenwood that the Kenwood still would play the HI Res ALAC format. I also confirm this when I converted my music to FLAC and downloaded them to a flash. There's a separate plug for this in the HU. The FLAC music files sounded noticeably different. But the thing that really sucks about a flash drive is trying to organize your library. This is why I'm seriously contemplating running a wire directly to the DSP. I would just have to pause the music when a call comes in. When using the Waze app with CarPlay - I would have to mute the voice on the iPhone. I would then control the music through my iPhone and not the HU. All of this just for a little more clarity from my music. As I type this I'm thinking that it really doesn't make sense to go through all of that hassle. There really isn't too much of a difference.