I wouldn't worry about the efficiency mis-match. Keep in mind that with a surround setup, you really need to calibrate the system (either with an SPL meter, an auto setup algorithm like the 990 offers, or both) even if all of the speakers are identical. The 990 offers +/-15dB of adjustment per channel, if I remember correctly (I'm not using more than +/-5dB or so, and at least 3dB of that is because I've got a mix of balanced and unbalanced amp connections). If the Totem is efficient and the Dalhquists are inefficient, you can probably expect to end up with some fairly different trim numbers between the center and the fronts. Once that calibration is done, however, they'll be matched up and it'll be a non-issue.