Well, I don't know your budget, but Meridian 500's pop up here from time to time for a mere pittance relative to how good they sound. I used one for a year into that very DAC and it was great.
I agree with Danlibl, without a stated budget its hard to make a recommendtion. However, I have over time had a ML-31.5, CEC-TL1, and presently use an Ensemble-Dirondo transport in my system. I find the Dirondo to have the natural timbres/smoothness of the belt driven CEC but also great dynamics/details of the older ML-31.5. There was a couple of Ensemble-Dirondo transports for sell here on the GON, that still might be for sale. I have heard your DAC with this transport and it was a great matchup. Hope this helps.
I upgraded from a Meridian 206 to a Sonic Frontiers SFT-1 with my ECD-1. It was a significant improvement and is in the low range of your budget. Another upgrade to consider is the digital cable. I upgraded mine from Transparent Premium to the Transparent Reference AES/EBU. The improvement was as much or more that the transport upgrade. You can probably get both at the high end of your budget.