Line-Neutral-Ground instrument to be plugged to a Line to Line power source
The most likely problem is wrong voltage. Line to line voltages are usually higher than line to neutral voltages.

Some old or unusual equipment may have problems if it's "neutral" connection is not close to earth potential but such equipment is by far the exception not the rule. Remember large parts of the world use unpolarised sockets so any manufacturer whose appliance couldn't tolerate it's "neutral" pin being away from earth potential would be severely limiting their market.

Fuses and circuit breakers in the appliance may be rendered less effective in such a situation but if there is a RCD/GFCI present then it should mitigate that risk. 

Overall if it's a modern portable appliance and the voltage is correct it will almost certainly be fine.