I'm uncertain as to how well connecting a sub to the DAC's RCA outputs would work. It would certainly function. But without clear information as to the design of the DAC's output circuits I would have some concern that doing so might have at least slight adverse effects on the signals provided to the Rowland amp, and thus to the main speakers, unless the circuits driving the two outputs are totally independent. That concern being heightened by the fact that as with the line-level inputs of most subs the input impedance of the F112's unbalanced inputs is low, in this case only 10K.
And I note that in the entire DAC manual the only statement that is bold-faced is "We do not recommend using both outputs at the same time."
And then of course there is the question of how good a match there would be between the sonics of the sub and the main speakers, about which I'm not in a position to comment.
Also, of course, there are other subs which provide speaker-level inputs, such as the RELs. However, the 525 amp is described as having "balanced topology implemented throughout all power and input/output circuits," which leads me to suspect that it may not be ok to connect the ground wire from such a sub to the amp's negative output terminal. And the amp does not appear to provide any other suitable ground connection point. In which case connecting that wire to a chassis screw on the amp would **probably** work ok, but again there is uncertainty.
Best regards,
-- Al
