There are lots of questions to ask here. Are you happy with the Qutest? Are you just seeking more? Is anything missing? Tonally, is they system good?
The obvious step would be a TT2 if everything is perfect and you just want more. If something is off or you want some other difference or the system is too bright, etc… that would lead us down a different path.
full disclosure, I am a dealer who focuses on DACs and have tested dozens. The guys who say there is “no difference” in DACs are welcome to their opinions. My experience is quite different and I do not believe I have golden ears. There is a lot of compromise in what DACs do in terms of detail vs staging and the question is what is your priority and the tonal balance of your system.