Problems with the IFI Zen Stream.. What's a better Alternative?

@dbb, I pay my ISP a fee for cable service so my visit was included. As I said, your router and modem may be okay but your cable signal frequency may be out of range. Mine was so a home visit is suggested. Some of my cable connectors were not tight so he replaced them. 

Totally agree with hgeifman, I was a AT&T tech for 40 years, recently retired. You could have the best modem or router inside,  but you have no idea how fragile the outside infrastructure is. Especially if you are still on copper cable.  There is so many connection points between your router and the central office that can fail slowly over time, you would not believe . 

Don't  trust the test that are ran remotely from some office when you call in to complain,  let them send someone out to test the sync at your router, and if there is a issue work their way back to the source. 

Your suggestion is well taken on bringing in the IPS tech for a home visit. They will charge me but less than buying a new piece of equipment.

Don’t discount that you’ll have peace of mind knowing for sure one way or another if your incoming signal is the problem.  Seems like a much better initial option rather than blindly throwing other equipment at the issue and hoping it magically works.  Best of luck in sorting this out. 

@dbb

Have you tried performing a factory reset? Make sure to follow the directions in the manual.

Also - have you tested the ports that the iFi's are connected to with a PC or other device just to make sure that the router / switch is ok?

Consider the Eversolo DMP-a6. It is a streamer wirh an on board Dac, but what it does sonically just as a streamer makes it worth it's $859 asking price. IMO