Not sure your Dali's need such a big amp as the 4bSST2. Not heard either amp you mentioned but I'd recommend doing what you can to hear both amps in your system before making a purchase. Modwright and Audio Advisor on the Bryston will let you return their amp if you don't like them. I have had two ModWright preamps and love their product; very happy with my current LS 36.5, but I've not heard Dan's amps. I'd suggest a Pass amp and Reno HiFi can help you and they will send you something to demo too... see what they have used. I have a Pass amp and have no desire to ever change it out unless I move to a newer Pass.
One of my local shops had the original Dali 400 in for evaluation and I liked them but they passed on picking them up. I remember it was a fairly lively speaker and I would be concerned with the wrong amp it could sound bright; especially being a big SS amp. They really didn't have a amp in house that was up to the Dali's at the time, but I could tell it had potential. I felt a tube amp would be nice on them.
Before I picked up my Pass I had an ARC 100.2 and that was a wonderful amp and I've dragged home some newer ARC SS efforts and the hybrid they had a few years back and the 100 watt SS 100.2 was the better; dragged a couple Krell's home too and they were not to my liking. The 100.2 is a Very nice amp. If you can find one of these you will be amazed and if you don't like it they sell fast so you won't be stuck with it. Really is a wonderful amp but my Aerials needed more power so I went to a Pass which is a better amp and my speakers love it.
If you can get a manufacture or retailer to send you a demo I'd do that first.
Good luck
