Hi @charles1dad
Good questions. I bought the Zenith Mk3 a few months ago, but effectively don't use the internal hard drive. 99% of my listening is new stuff, so I stream Qobuz. It's also the case that many of my CDs have since been remastered and rereleased to Qobuz, so sound better streamed than ripped. So, if I had to buy again now the Pulse series would be my preference.
I also added a 2nd hand PhoenixUSB (with great success), so I would look seriously at the Pulsar, which reportedly bundles a USB reclocker. You'll need a good USB cable though.
I recently trialled Roon. Basically, Sense 2.x sounds better than Roon - many would agree with this. The only thing I miss about Roon is their rich DSP feature. We all need a form of tone control occasionally.
Interestingly, one of the biggest gains I made was only a couple of weeks ago. I replaced my 25 year-old entry-level mains conditioner with an Isotek Gemini to feed my Innuos boxes. Was only £300, but brought about huge gains. Innuos put huge emphasis on the quality of their internal PSUs, but it seems to me that they're still very sensitive to mains noise. A decent-ish shielded mains cable will also help. Belden 83803 is very affordable.