The balance control is located on the remote only(not on the unit.) The display will show two sets of levels when it is utilized.
I have owned my unit since July and absolutely love it. It is quiet and presents incredible soundstaging, depth and harmonic richness(instruments sound real.)Voices are about as good as I have heard.
I listened to the ARC Reference II and I personally thought the Calypso held its own. The ARC seemed to impart a touch of forwardness in the mids that seemed to spotlight voices a touch too much (even though the ARC sounded pretty dang good!) I thought it outperformed the BAT51se and certainly(by a wide margin) the ARC 16. I never compared it to the ARC 25 but would assume the comparison with the Reference II was enough.
I previously used a Audible Illusions L-2 with a mono switch but I have never missed it.
The rest of my system consists of Vandersteen 3a Sigs. w/ a pair of 2wq subs, an Ayre V5x using a modified Sony xa777es for reference.