I think the I2S and I2Se have different connectors. I'm using an ST connection out of my transport fed into an Assembledge D2D-1 upsampler/jitter reduction unit. The D2D-1 has the same I2Se output as the Sonic Frontiers input. Even my $200 DVD player sounds good as a transport into this set-up.
Suggest you look into a D2D-1.
Suggest you look into a D2D-1.