If you have connected both 5.1 RCA and HDMI outputs from the 105 to the 7005, both are active and either should be selectable by switching among the 7005 inputs. When you select the 5.1 RCA inputs, you are using the DACs in the 105; when you select the HDMI input, you are using the DACs of the 7005. There is no advantage to using balanced cables unless the 105 is a very long distance from the 7005. Consult the 105 manual about using the stereo outputs for the front LR channels of 5.1 so you take advantage of the superior DACs.
You should be able to compare the sound with the 105 DACs to that with the 7005 DACs just by switching among the 7005 inputs. Be aware that there is a bug in the speaker distance settings of the 105, so it's easiest to start by setting all the distances to 0. A fix is said to be on its way soon, and if you have the 105 connected to the internet as it should be and you set the menu to update firmware, you'll get a notice when new firmware is available.
Finally, if you don't have analog sources, you might consider using the 105 direct to your amps and selling the 7005. At least you should try bypassing the 7005. The 105 can provide speaker configuration, bass management, and fine volume control.
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You should be able to compare the sound with the 105 DACs to that with the 7005 DACs just by switching among the 7005 inputs. Be aware that there is a bug in the speaker distance settings of the 105, so it's easiest to start by setting all the distances to 0. A fix is said to be on its way soon, and if you have the 105 connected to the internet as it should be and you set the menu to update firmware, you'll get a notice when new firmware is available.
Finally, if you don't have analog sources, you might consider using the 105 direct to your amps and selling the 7005. At least you should try bypassing the 7005. The 105 can provide speaker configuration, bass management, and fine volume control.
db