You have to set the channel volume for your preset's and save it to the desired bank. Scared the crap out of me first time i started switching through the preset's. It's just one of those bug's with the SV you have to work out on your own. Remember "Channel Volume", then you can set your master and leave it where you like. Just remember to turn down the master when you search for other sounds.

Just come across this post after recently purchasing same gear as the guy asking the question,..........and yep,..same `problem` here,..really quite annoying as surely line 6 can somehow release a patch for the software that equalises the sound level of ALL patches,.......i do use the spider edit software and thats quite helpful,..but again,,its a lot of messing about and im never quite convinced after a save that it actually saves properly,.....i spent ages trying to balance 8 patches between 2 banks of four and it just became endless as when you switched back a bank the sound levels were erratic again,...also i have noticed the volume level can jump occasionally on its own,.....it becomes nightmarish in this case,..this is in my opinion is a real problem if your playing live with this thing as its quite important to keep ALL patches at the dsired level,.....i dont see many other posts regarding this jump in volume issue so now im wondering if its my unit thats faulty,.....problem is it doesn`t always do it! hence not much point going to all the trouble of returning to be told no fault found,........if im going to lay out this sort of money on this gear then i need 100% confidence,...not 99%,.........ohh,..and another issue while im here,..has anyone had their FBV shortboard throw a `wobbler`,...as in it switched randomly,......the `up` became `down` for patches as an example!!! Also the wah function stuck on, even though indicator not lit,...then after switching back to light the wah light on the volume pedal didnt work,.. it was a little too confusing to try to explain everything that went on,...just wondering if anyone had something similar happen with theirs,....the `good` news is it hasn`t happened again,..maybe the update to v2.00 did something,..god only knows,.......but my main concern is the, sometimes, HUGE jumps in volume between patches even though they were `balanced` within the spider edit software. Cmon,..line 6.........give me some sensible answers as i dont want to have to endlessly tweak settings!!  thank you.