i want to buy a vox valvetronix 100 watt amp head to plug into my marshall cabinets.

my question is would they be compatible with each other.
my speakers can handle 120 watts
yea. Any head will work with any cab, as long you have a 4 Ohm/8 Ohm/16 Ohm jack on both. Idk what you would have, since idk the config. of your cab.