I've got a Glockenklang onboard pre ( which I really like ). It seems though that the volume on the preamp is quite low. I've got to crank it just to be heard above a guitar and drums in a quiet jazz trio. By comparison, my fretless ( packing a piezo ) is loud enough at half volume. I'm using a 200 watt Genz Benz combo - which I think should be good enough for a jazz trio... Would a low battery be causing this low output?