Does Leica specify the maximum safe voltage for the M10 accessory shoe flash contacts? I would like to experiment with older "hot shoe" small flash units that apparently will fire (using the flash's manual and automatic modes), because the center and side contacts on the M10 (and maybe all digital M cameras?) are "backward compatible" with older hot shoe flashes.
I used a small analogue multimeter (with a low resistance of only 2 kilo-ohms per volt, on the 250 VDC scale, so it applies a 500 kilo-ohms load to the flash's charge circuit) to "approximately" measure the charged voltage on the hot shoe contacts of two older flashes (Vivitar and Metz). They both measured under 50 volts DC. The true "open circuit" voltage actually may be a bit higher, if I measure with a much higher resistance digital multimeter, but it is unlikely to be over 75 volts. The (approximate) 50 volts I measured on those old flashes may be OK, but before trying them I need to know what Leica advises for the M10. I do not want to fry any expensive electronics.
Any experience and advice from M10 users who have tried simple, older, hot shoe flashes, will be appreciated.