I currently only have instrument cables so i would have to buy a speaker cable to have the mono out. I may do this anyhow still though. I would prefer not to have to worry about anything and to be able to use stereo effects if i desire. I only play at home so i'll never have a long cable.
On another note, does using input 1:guitar, input 2: Same or input 2: variax have any bearing on the ouputs using 1 xlr>?