If you are doing over 10 people once a month or more, then you should have a distributed cue system. If they are performing their own pieces, then they are under direction and blend themselves, but if they are performing along to a track, then cans are important, and you want to be professional.
Here are two circuits:
The Simons circuit is quite simple with the input connected to the CW side of a 1K audio taper pot through a series 330 ohm resistor. CCW is common and the wiper feeds the cans. They use a 2W resistor and 3W pot.
A classic studio in NYC used the following circuit in their custom boxes:
Input feeds the CW side of a 5K linear pot, CCW to common, wiper feeds the cans through a series 120 ohm 2W resistor, and there is a 620 ohm 2W resistor between each side of the cans and common. That circuit provides a load even with nothing plugged, but the pot takes all the juice when turned down. That is why I keep all pots high or full CW.
You can up the wattage ratings of everything, although it is tougher to find higher rated dual pots, so perhaps you go like the ProCo box where there are two mono pots feeding two outputs. There is a switch for stereo or mono.
Cost it out for parts, and you might do better making some customs. The big hit is the headphones anyway. Also look at the Furman or other simple self-powered headphone boxes. That 4CH Rolls costs the same as a ProCo passive I think, and a Simons is $300 for 4 channels.
What I advise studios if they HAVE to have a distributed system is to buy 1 or 2 Simons for the bulk of the sessions, and a bunch of Redco or ProCo for the large gigs. Keep all volume pots UP!
Mike