One more... Ken Rockwell measured a channel imbalance of around 1.5 db on the DAC-1 HDR (worst case), if I'm reading correctly. That is more than others measured and could admittedly be audible for trained listeners under ideal conditions, but it is still very low.
If you are getting significant channel imbalance, have you tried adjusting the calibration? Here are directions Benchmark sent me a few years ago:
Directions for calibrating
Submitted by EliasGwinn on Tue, 2011-03-08 14:01.
Directions for calibrating the DAC1 USB:
WARNING: This procedure involves playing a test tone that should not be played through your speakers.
1. Disconnect all analog cables from the DAC1 USB.
2. Download this test tone (1 kHz sine wave @ -20 dBFS):
3. Play the test-tone through the USB input of the DAC1 USB. Make sure all computer/software volumes are set to 100%.
4. Make sure the rear-panel ‘output mode’ switch is set to ‘Calibrated’ (the upper most position)
5. Measure the AC voltage between the center and ring of one of the RCA outputs.
6. Adjust the corresponding calibration trim-pot until the voltage measures 0.2 VAC.
7. Repeat steps 5 and 6 for the other RCA output. Your DAC1 USB is now calibrated.
8. Delete the test-tone from your computer (or at least remove it from your media player library) to avoid accidentally playing through your speakers it in the future
9. After calibrating, if you are connecting the DAC1 USB directly to an amplifier and/or active monitors, be sure to set the rear-panel ‘output mode’ switch in the ‘Variable’ position (the bottom position).
Edited by VandyMan - 5/15/14 at 1:11pm