Recently got a BA 108 and had the opportunity to use it at a band rehearsal. The rehearsal space is a small room with very few flat, reflective surfaces (drummers unfinished basement!). Two guitars and well muffled drum kit. It performed very well (the 108) and I had the volume at 10! No clip/fart/rattle at all! Could hear it through the guitar amps just fine! Best little amp I have had to date! Has the good Ampeg sound and I can pick it up with one hand!
Are you using an ultra low output bass? These should start to give up around the "4" range.