I do like the idea of SGC option as the Sonic Transporter is a Roon core, that allows you to connect optically to your DAC rather than USB, thus giving you complete galvanic isolating, in turn giving you the best black background, I would think.
This is a much more costly option than Nucleus direct to DAC. Without out hearing it first, I'm not sure if it's worth the additional costs. Maybe more money should be spent on a better quality DAC?