Depends a LOT on what you are playing, where, and who you are playing with. A 350W head should give you what you need a in a small room, but you might need a 15 cab. Alternatively, playing a big gig with two guitarists maxing their heads out might need 500w and a 4x10 to get you heard. Also, it can vary a lot depending on manufacturer, an ashdown or laney head will be quiet where as an orange or Harttke will be loud. Tough question!