I was playing around with my Yamaha S1800 and just discovered it has an option for frequency cutoff for SACD playback. The default setting is 100kHz. It sounds good, but 100kHz seems a bit high to me. I have options for 60, 80, 100 or 120 with this setting. Can someone advise on what would be optimal given these choices? I'm thinking 60 or 80 for 2ch SACD playback. Thoughts please.