Well, I can give my opinion but it is nothing more than an opinion. I think that this is a three dimensional question. It’s not simply better or worse, as there are a lot of different aspects to the performance that may vary based on taste and system synergy etc. I spent a few nights listening to the Stellar Gold DAC during it’s development and doing A/B testing with the DSD Mk2, mostly.
Objectively, the Stellar Gold DAC has much lower measured noise and distortion than a DSD Sr… Whether or not this subjectively important hinges on your system setup and configuration to an extent. The Stellar Gold DAC has a very “hifi” presentation with a very black background, tight, ended low end and airy top end. It seems more sensitive to cable/source quality and incoming jitter than the DSD but I wasn’t involved in those measurements.
The directstream DACs and a “smoothness” and musicality that are unique. The bass on the original DSD Sr. can have a bit of bloom a be a little “tubey”. There is a vibrant midrange. A bit less sense of sparkle and high frequency extension.
I will say that I significantly prefer the DSD Mk2 to the Stellar Gold DAC but prefer the Stellar Gold DAC to an unmodified DSD Sr. but your mileage may vary.
I think that the Stellar Gold Preamp is a huge winner in my book and I want one at home and prefer the sound of it to our BHK Pre. It also has a much lower noise floor and totally black background to the sound and is very open an lifelike sounding. If you’re looking for added flavor or warmth, it doesn’t have that. I wouldn’t say it’s analytical or etched sounding but it’s definitely very clean. To me, this product is a “wow”.