I am a Krell Foundation owner. Krell just recently offered to upgrade our Foundation processors to a 4K version along with other enhancements for $1,000.00. I took advantage of this offer as it is significantly cheaper than purchasing a new processor. Also I wanted to support Krell for giving us an easy upgrade path and keeping our equipment relevant. Plus the sound from this unit is incredible (IMHO). You do have to send your unit to Krell to have the upgrade performed.
Krell Foundation 4K, Parasound Halo A21 and A51, Martin Logan Ethos x 4 (L,R,LS, RS), Martin Logan Stage X (Center), Kimber Kable 12TC speaker cable; Velodyne Digital Drive 18 Plus sub, Oppo 103D, Kimber Kable KCAG interconnects; Panasonic TC-P65VT30 65" monitor.