DDC Sound Improvements???

Same here, I’m in the process of upgrading (tricking out) my Technics SL-100C turntable.

@mitch2 ’s comments below are an excellent summary -- pretty much all one needs to know on the subject

I had a Node2i moded with a TeddyPardo LPS connected via coax to my PS Audio Directstream DAC Mk1 moded by APS Transformers. I tried a Denafrips Hermes 12th DDC,  connecting to the DAC with I2s. I did not experience a significant improvement in SQ with the DDC.  The LPS mod made a huge difference however!! I have since upgraded to an Eversolo T8 streaming transport, connected via I2s and that has been a significant improvement in SQ. I first connected the Eversolo using the ethernet port.  I then switched to using the SFp input using a inexpensive  TP Link fiber media converter. That resulted in a slight improvement in SQ.  I have a high quality FMC from LHY Beatachic, with internal LPS,  being delivered this week.  It's going to be interesting to see if replacing the cheap TP FMC and wall wart with a quality FMC makes a noticeable difference in SQ. Or if I just wasted $500!!

USB to your Gustard X30? or -(Maybe I am reading it wrong but it may have I2s output too?) If it does you can use that connection to your X30. I see it does have a clock out feature so down the road you can get a nice outboard OCXO clock instead of the DDC for added refinement. 

I2S may work fine with some components but, in general, is over-rated as a connection protocol between two audio components and is not likely to significantly change the overall sonic presentation of most DACs compared to an optimized S/PDIF or USB connection (IME). 

@fthompson251, I’ve been seeking and taking your advice for years on matters audio. Because of your and @mitch2’s posts, it made me look into and figure out exactly what an asynchronous USB connection is and more importantly what it does.

If one could figure out away to add a nice outboard OCXO clock instead of the DDC for added refinement. That right there got my attention.

Any OCXO clock recommendations? Anyone? Anybody a fan of LHY AUDIO?

Yes, I would look into the LHY models. Alvin should be helpful in leading you on that decision. I honestly don't know much about master clocks other than getting the best OCXO you can afford. Denafrips makes a couple master clocks too.