A little while back I went and purchased a yamaha b-100. It was very cheap and the tone was pretty massive for what I paid (used to be able to feel the bass throughout my 700 sq ft loft). But recently I've been noticed the amp has gotten much more quiet. Almost no tone. At first I thought it was my amp playing tricks on me but now my 60 watt amp which had trouble keeping up before is much much louder (play through a big muff, dry signal to the b100 high frequencies through the 60 watt univox w/ 2x12). Seeing as the amp is almost 30 years old now I'm thinking it might be in need of a rebuild. What do you think?