I see your dilemma. I suggest you don't upgrade until you feel you have to, that means until you have enough DSD material to warrant the upgrade. Most good material is still only PCM.
If you are looking for a more meaningful impact, consider upgrading your source because the TotalDac is extremely revealing of the source. I like the Sony you have a lot. In fact, I own a Sony ZX2 player and I love it with my CIEMs but the Sony is roughly on par with the Auralic Aries I have, meaning it sounds good but it doesn't do your TotalDac d1-dual justice.
There is a an Aurender dealer based in Illinois who will send you an Aurender N10 for home evaluation with no obligation (you just have to cover shipping). The unit is already pre-loaded with 1 TB of music including a full library of DSD material. Once you hear it with your TotalDac, you will see what I'm talking about within 30 seconds. It may have an even greater impact than going from dual to monobloc. The reason I bring up the N10 specifically is that it can process DSD to PCM internally. This means that if you don't have a DSD-capable DAC, you can still play DSD. If you are interested, PM me and I will provide you his contact info although you will have to wait your turn because this demo unit is headed my way.