Oppo Udp-205 HDMI ARC volume issue

Greetings,

I am using an Oppo UDP 205 HDMI ARC connection to route sound from the Sony TV to the Oppo to utilize the DACs on board. From there it goes to my Luxman C02 stack. When utilizing the connection I do get sound but the volume is so low I need to turn the amp up three quarters to get to a decent listening volume. This is while the TV setting is on external stereo- not tv speakers. Any idea as to why this might be ? Connecting the tv to an aux input on the amp relieves this issue with 1/4 volume being almost too loud, but bypassing the Oppo all together. Appreciate the thoughts,