Are you using the TVs internal speakers? The ARC should be feeding the 5005 with the audio signal from your TV but the volume would be controlled by the 5005 remote. Of course if you are using the internal TV speakers the volume would be controlled by the Samsung remote unless you programmed the 5005 remote to control the TV. You might have to switch the 5005 remote into "TV control mode" to control the internal speakers of the TV.
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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