New DAC or new cable?

Your AX-7e provides rca inputs, as well as xlr inputs, and presumably it converts the unbalanced rca inputs into balanced signal pairs, since it has balanced internal signal paths. So why do either? Just use an rca-to-rca cable.

Doing that would result in some increase in the possibility of ground loop issues, compared to having a balanced interface, but chances are that won't be an issue anyway, especially if the cable lengths are not especially long, and you use good quality (not necessarily expensive) shielded cables. (Susceptibility to ground loop problems is dependent in part on the resistance of the shield or other return conductor in the cables).

And more importantly, I would expect that using an rca-to-xlr cable would result in an unbalanced signal being put through the balanced internal signal path, which is definitely undesirable for many reasons, including sacrificing much of the power capability of the amp.

Regards,
-- Al

11-29-11: Almarg
... including sacrificing much of the power capability of the amp.

Correction: I should have included the word "possibly" in front of this phrase, as it depends on how the design is implemented.

Regards,
-- Al

Well said, Doug, including the inside joke :-)

BTW, I should add that my earlier reference to ground loop effects that are more likely to arise with unbalanced interconnections, which as I indicated can be sensitive to cable differences, pertains not just to the possibility of hum problems, but also to the possibility of low level grunge at higher frequencies, which can result in effects such as reduced "background blackness." Most likely that will not be an issue, as I indicated, but it could be in some systems, and perhaps is one reason that some people have reported better results when providing balanced inputs to the amp.

Regards,
-- Al