I realize this is an old topic but I just recently acquired a mixer and am going to connect a DM10 module to it. The same old question comes about the outputs. Either the user manual is wrong or the overview, feature and specs on the alesis description page (website) is wrong. The overview describes the module as having 2- 1/4" stereo balanced main and aux outputs. Stereo connections are never balanced as I'll explain later. The user manual however says to use TS cables. The headphone connection is a single 1/4" TRS stereo connection, unbalanced. Using TS cables on a balanced output or input for that matter kills all balancing (no opposite polarity differential). You need TRS cables to achieve a balanced signal or an unbalanced single jack stereo connection. Tip + (hot channel), Ring - (cold channel) and Sleeve (gnd) for a balanced connection or Tip (L channel) Ring (R channel) and sleeve (gnd) i.e the headphones (or single TRS 3.5mm connections). There are quite a few ways balanced lines are designed, Impedance Bal, Ground Compensated Bal, True symmetrical Bal, and the list goes on, but, in all cases they require 3 wires to be balanced, thus a TRS or XLR cable. TS cables have only 2 wires, Tip + and Sleeve (gnd) as does an RCA connection. Besides the single jack unbalanced stereo connection (1/4' ur 3.5mm TRS)' you can have a two jack stereo connection L and R, normally unbalanced RCA (only has a tip and sleeve) or 1/4" TS jacks i.e.the DM10 main and aux outs. TRS jacks work on unbalanced connections because of the + (hot)signal is at the tip, the ring is dead, and the sleeve is always ground. Notice however that TS jacks work only sometimes and sometimes not with balanced connections (they work only on gnd compensated or impedance balanced designed connections). The reason is a balanced connection uses a signal on both the +(tip) and - (ring) and compares the difference in voltage between the the two since they are opposite polarities. The + and - voltages have to match, and any other voltages are not used ie.e stray RF etc. thus balanced. This achieves much less noise and hum in a line. The TS connection does not compare any signals. Only one signal path is used normally at + Tip and the Sleeve is just the gnd thus noisier on long runs where they can pick up stray RF noise.
So I think the DM10 has unbalanced outputs just like the left and right channels on any stereo RCA connection except using 1/4" jacks instead, thus the TS cables. The only way to know this for sure is to open the box and see how the connectors are wired.
Now the other question remains is what is their maximum output +13dBu/11dBV or whatever if you want to achieve "unity gain" between connections. Sorry this is so long winded but its necessary to understand apples to apples.