I'm planning on upgrading my audio setup for my headphones and I have a question about the PS4's audio.

I am planning on purchasing some AKG K612 Pros and I'm trying to figure out if I need to purchase a new DAC to use Dolby. I looked through Dolby's PS4 Audio Guide and found a few answers, but I am still unsure about a few things. I have a FiiO E17K Amp+DAC combo currently. According to Dolby, Surround Sound is available through Optical, but it didn't state anything about USB. The issue comes with the fact that the E17K, unlike its predecessor, does not have an S/PDIF input. This leads to the questions I need answered:

1. Will USB audio support Dolby Surround?
2. If I do not end up being able to use the E17K, I am planning on purchasing an SMSL M3 Amp+DAC. Is the sound card in the PS4 able to support Surround Sound if connected through an optical output, or will I need to purchase extra hardware to make it work? This seems like an obvious answer, but I just need to make sure I'm not missing anything before I purchase another unit if I need to.