x RELIC x
Headphoneus Supremus
I can enable ACG when I'm in SE mode and there's a noticeable difference to my ears. May completely be a placebo, but I swear that it sounds better to me. When using the balanced jack, I do prefer the regular "balanced" mode rather than the ACG mode. To make sure I wasn't crazy, I just spent the last hour listening in all of the combinations (3.5mm / 2.5mm / ACG / balanced) and could definitely hear stuff. Not such a wasted hour. The sound is fantastic regardless of mode!
Every thing I've read about the DP-X1 says ACG is balanced only.
'In addition to a 3.5 mm headphone jack, the DP-X1 also features a 4-pole, 2.5 mm output that supports both BTL (Bridge-tied load) and ACG (Active Control Ground) balanced drives – the latter is said to offer greater stability, more space and dimension and a clean, crystal clear sound, with more definition in the lower registers."
Including Onkyo's own website:
http://www.onkyousa.com/Products/model.php?m=DP-X1&class=Accessory&source=prodClass
"Balanced Drive Options
Balanced 2.5mm 4-pole output supports the more standard Balanced (BTL) drive as well as the more esoteric ACG (Active Control GND) drive.
ACG drive gives greater stability: increased S/N ratio; greater spatial dimensionality, and clean sound; greater deliniation for lower frequencies in hi-res audio, and overall robust and taut sound. BTL drive supplies increased power.
Power gains and increased sound separation associated with balanced output are repurposed to create increased stability for a clean signal and greater sound clarity, especially compared to unbalanced drive."