IFI Zen Stream users

I have a Zen Stream I bought about two weeks ago. I am using the dac in my Mac MA5300. I started using SPDIF when I first got the unit, then moved on to USB. Web radio often delays a minute or two before it will play. Spotify delays are much less, but can clip a second or two off the begining of songs. Delays seem shorter with SPDIF. My previous stream was a Yamaha WXC-50, and didn't exhibit any of those issues with SPDIF (USB not on that unit).  Anyone else had, or having these issues? Ideas? Thank You!