Jamming???
500w = nothing, u'll never hear again after turning that amp on... maybe if it's a bass.. then it's not that uncommon...
at max 100w.. even that may be much for jamming..
what music do u play?
and what kinda amp are u thinking of? head and cab? combo? 1x12 2x10 2x12 4x12 etc?

for jamming(with others) i would use a 50w amp with a 2x12 cab.. but i would have lifted the cab alittle up from the floor.. then it sounds better and louder.. 50w and 2x12 is more than u think...

if u meant jamming alone at home.. i think 25-50w.. and 1x12 is enough...

But on stage i would use 4x12.. but maybe not on full volume.. but i would miced it up with a sm-57 and have alittle guitar in the PA...

NB; this is tubeamps.. i have no idea how a hybrid/transistor amp would be... some says they are louder on low volumes and lower on high.. but i don't really know.. TUBE MATTERS!

Sivert Skaaren
aka Acron