simple stereo to mono box

Which schematic are you looking at svart?

I'm looking at as080

Usually it's 2 snare mics or 2 tom mics. Sometimes 2 cab mics for bass.

So I'm talking post pre line level. I currently use the console. The groups are a pain because I loose panning ability. Aux requires some extra patching which is no problems but of late I've been feeling I prefer going direct to the converters and use the console for mixing and monitoring.

Resistors would be fine as well. What values would be suggested for 2 channel.

Either way I'd prefer passive to suit remote tracking as well.

I use 300Ω in the control room module to sum stereo to mono. 1k is also fine. I would make sure they are precision or matched very well.

The value depends on what the driving impedance and the receiving impedances are. Lower resistor values are better from a noise standpoint, but the lower the value, the more power the driver circuit wastes and can trigger other issues with heat and distortion.  Also, the higher the summing resistor value, the better the crosstalk specs (which might not be that important since you're summing anyway..) but drops the driving ability of the channels being summed.

For line level(and impedance) I would use more like 4.7K to 10K for summing resistors. They are a good balance between impedance, crosstalk and current drive requirements.

If you went higher to say, 47K, you'd get even better crosstalk specs but you'd need to turn to active summing to achieve usable levels and current drive abilities again.

Probably doesn't mean much but why not do it the right way anyway?