I have both a 990 and a 970. I've had the 990 longer and have had absolutely no issues with it. It is truly a fantastic piece of equipment that does exactly as advertised. However, the same cannot be said of the 970, unless you count "audio dropouts and complete freeze-ups" to be exactly as advertised. If you are thinking of getting a 970, make extra room for the larger 990 and spend the little extra money. You will be much more satisfied.
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HT: Outlaw 975/7125 | Sony 55" SXRD | Roku Ultra | Sony BDP-S790 | Mirage OMD-15 (fronts) and Prestige 4 + Center Channel | Outlaw LFM-2
LR: ARC Reference 1 | Emotiva XPR-2 | Music Hall MMF2.2 | Oppo BDP-83SE | Polk XRt12 XM Receiver | Emotiva XDA-1 DAC | Sony HAP-S1 (digital audio player) | Sansui TU-217 Tuner | Magnepan 3.6R w/Mye-Stands | SVS SB-16 sub | BA VR-M90s | Audio Quest 72db speaker cable
Office: Drobo 5N running as PLEX media server
Closet: too many pieces to put all into place, I need more rooms