There are NO DAC inside, so only Analog line-in.
Never heard about TU-03. The little brother is TUR-06: half size but hybrid while the TU-05 is "Tubes only" (no transistors in the Amp section like in the TUR-06)
As for Headphone-out, it ship with 3,5mm jack, but... I added a big FAT XLR (non Balanced) because I find the 3,5mm jack way too fragile with thick full size headphone.
Wow, you add your own xlr...I wouldn't dare breath on it internally!
Would the maker not provide a connection option at point of purchase? Without a 6.3mm I couldn't even consider this make of amp anymore :-(:-(