I have a Vox DA5 and a Weber Signature 8S Alnico on its way to me. Two questions: Do I have to enlarge the speaker hole opening? Or can I mount the speaker where some of it is behind the fiberboard? Will this new speaker reduce my battery life? If so, by how much? Most of the time I will be playing softly on the 0.5 watt setting. Any other tips before I start this project? Thanks!!