I an owner of an Auralic Aries G2 (not the 2.1). And I pair that with an external dac the Chord Dave.
Even so I would definitely recommend the Vega G2.1 over the Aries G2.1 if the budget for an external dac is $2k.
I can’t see that an external dac would outperform the Vega G2.1. So unless you do like the upgrade ability and consider later playing around with even more expensive dacs or would like a certain “signature”.
In my opinion the Vega G2.1 has excellent sound reproduction and a great streamer — I’ve only heard the G2, but if there is any difference it should be positive difference. Most Vega users do not see any point in adding an Aries to the stack since the Vega is very close to, or actually is perceived by some, as the same performance.