i have a ss amp that puts out 4 ohms and a g412 crate cab at 8 ohms im not sure how the cab is wired i wanan say its series/parrell but im not sure.if i were to rewire it so that it had (2) 2 8 ohm speaker in parallel with 2 imputs would that work? and or be louder?
two 8ohm cabs wired in parallel will result with a Req of 4ohms, and give you maximum wattage. Just make sure that the speakers can handle that 2.21 jigawatts of power
i'm pretty sure that if the SPEAKERS are 8 ohm, then you can drive them with your amp because you don't have to match if the cab is a high ohmage than the amp. If this is the case, then the speakers are wired parallel. if they are wired series, it's 16 ohms, and still OK to drive with your amp. Basically i think you should be fine running a 4 ohm amp through whatever cab you have.

IMPORTANT!!!!!!!!! i am new to the whole head/cab thing and i personally have a matching ohm setup so do not try this until someone can either verify or say i'm wrong (i take no offense) so what i said COULD potentially **** your amp up, but i don't think it will
My Guitars:
Gibson Les Paul Studio
Epiphone AJ
Ibanez Strat Copy

Orange Tiny Terror Head
Old beaten up Peavey cab
Marshall MG30DFX
should be fine,
i have a 4 ohm head
and a 16 ohm cab, nothing
bad has happened yet.
well what im saying is i feel like my amp isnt loud enough,when i play with drums another guitar and bass and vocals its hard hearingit somthimes...i figured if i matched the impediance it would be louder fyi head is 120 rms cab is only rated 100 so i figure right now if im only at 8 ohm on the cab aint i olny geting 60 watts of ss power? but if i wire it up in parallel then i coudl get my full wattage out of it i just prolly shouldnt crank it to 9 or 10 right? somtone help
SS amps dont have the same impedance matching issue as tube amps. An amp made to run a 4 ohm load but pushing an 8 ohm load will have less volume. They wont blow up this way just dont push as hard. Its why you see so many SS amps with 4 ohm speakers less to push so can make a smaller cheaper power amp.
You'll be fine, but check the rating on the cabs. Some cobs are only rated for X watts, and if you wire them to get 120 watts you might blow something up.