A couple of thoughts:
- Y cable is BAD. Before you even consider a new DAC, see if there's a way to connect to multiple systems without doing that. Looks like the SMSL has balanced and single ended outputs. On SOME DACs, using both doesn't degrade sound (on some it does).
- There does look to be significant improvement possibility based on your upgrade budget. But you need to decide what kind of sound do you like - the R2R sound or the SABRE DAC like sound -- and then there are options.
On the R2R side, the Schiit Gumby is a good option and I enjoy that DAC very much. The Mytek Liberty has an ultra detailed SABRE chip in it. Totally different approaches.