Next step? Amp or Streamer or…

@burtlake 

Nice system!  Depending on your budget, I would look for Innuos Pulse or Aurender N150 or N200. Audition them with a return policy and see if you are able to hear substantial improvement with your Pontus II DAC. A good quality USB Cable + PC is just as important in this equation. 

As far i2S, hand shake between two components can be challenging. HoloAudio Red Streamer / DDC comes to mind. I wouldn’t get too hung up on i2S…USB connection with a good cable is just as good with aforementioned streamers. 

Good luck! 

+1 for Aurender.

I would not worry about the connection type… especially a new and relatively unusual one. The difference in sound you will get by carefully choosing a great component will vastly outshadow a special connection type. Also, well established ones will have lots of choices of excellent interconnects. 

Dean,

I'd ask what you are dissatisfied with.  Bass, output level, transparency?  What have you heard you liked that's better.

You may also be feeling an itch to change for the sake of changing.  Maybe it's time to seek out a new integrated instead and keep the Eastern Electric in rotation?

Thanks all for the thoughtful responses -  lots to think about.  Will post specific feedback shortly

@lalitk @ghdprentice Appreciate the specific and helpful streamer recommendations and thoughts on I2s. I will look to arrange in-home demos and report findings over the next few months