4K is real, but the difference in resolution at normal viewing distances can be hard to discern. The larger color gamut with HDR is much more accurate and detailed and it is the future of video IMHO. One of the best things about the 976 is it's currency with connectivity as far as HDMI 2.0b and HDCP 2.2. If he already has a 4K/HDR TV he is wasting resolution with the 975.
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Music system
Model 990/7500/Magnepan 1.6 QRs/Technics SL1200 MK2/Aperion S-12 Subwoofer/OWA3/Sony NS75H DVD
APC H15 Power Conditioner

TV System
Large Advent Loudspeakers/ Polk center/Monoprice surrounds/Panasonic Viera 42 inch/Onkyo HT-RC260/Sony BDP S590/Directv


Home Theater System
Onkyo PR-SC886/Outlaw 7125 Klipsch RF-82 L/R,RC-62 center, RB-35 SR/SL, BENQ HT1075, Outlaw LFM1-EX/OPPO BDP-83/Directv
Harmony ONE
Blue Jeans and Monoprice interconnects
APC H15 Power Conditioner