Originally Posted by
WackyPacks 
Insignia NS-DXA1-APT includes with the instructions a separate piece of paper that reads as follows:
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For the best picture and sound performance:
...If you only have an RF connection to your TV:
Connect the supplied coaxial cable to the To TV (RF) jack on the back of your converter box, then connect the other end of the cable to the Antenna IN jack of the TV. For the best performance with the connection,
1. Change the Audio Output option to MONO.
2. Set your TV volume at mid-level (half-way between the quietest and the loudest setting)
3. Use the converter box remote to control the volume.
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If Insignia suggests using MONO, it would appear that there is something wrong with STEREO when using the RF jack. I know with the regular NS-DXA1, the volume was reduced dramatically in STEREO. With the APT, there seems to be no difference in volume between STEREO and MONO. There might be a defect somewhere else, but my brief usage did not reveal it.
Apparently, there is no issue when connecting via RCA jacks.
If anybody knows how I can determine the defect, feel free to post the information. The manual from the Zenith 901 that I have never mentioned anything about switching to MONO. So to be cautious, it might be best to avoid the Insignia APT if there are Zenith 901's in your area.