PRE/PROCESSOR ADVICE PLEASE?

Check out the Anthem AVM90.  Best pre I have had in my system and it integrates extremely well and phase aligns subwoofers to mains.  I have had many pres, but this thing just sounds better.  Not super pricey but definitely not cheap.  

Regarding your question about the Krell Evo 707.

I have had one for over 12 years. I still use it everyday and love it. I purchased the 4K Krell Switcher to update it for 4K. It works great with my new Sony 83" A90J OLED. I use Krell Evolution  mono blocks with the 707. The sound is spectatcular; Fast, vibrant, lifelike, clear with super tight deep clean accurate bass. I use it for 5.1 and that's all I need. I can't imagine a better sounding pre-amp/processor. Be aware, it can be quirky, like many ultra high end hand built units. I have brought it in for repair at Krell a few times. It remains the best sounding upgrade I have ever made to my music and home theater system. The terrific sound  performance of the Krell 707 is immediately  obvious. You will not have to strain to appreciate how good it sounds. I have participated in this hobby for over 45 years.