thanks for the helpful advice. i will try it. to answer a question, it only has happened twice on me with my active bass. it has never happened on a passive bass. now i have been using that amp a lot and i always push it hard. i play in a very loud band so this amp and all my others gets pushed to the max. it has never happened on a gig, just at home, and after it happened it was good to go. still ran it at the same volume. it seems like it happened when i tried to start out that loud instead of bringing the volume up.
Try cleaning the preamp / poweramp jacks thing and patching in and out with them and see what shakes out. So it only happens with your active bass? Then another dumb question. You are using the -15 db pad switch I assume? I still think there might be issues with the front end when using hot active basses.
Seems like you shouldn't have to bring the volume up. It should just start kicking at whatever volume you have it at. At least with my passive P it does. I'm still at 8 ohms though. Hoping to PU another HX115 HyDrive this weekend so then I'll be at 4 ohms and we'll see if mine acts up.
Maybe if it only happened twice and has been fine after that, it's OK. IDK though, if I was having a problem using an active bass, I'd sure want to crank that sucker with it and see if it cuts out. Any amp is a no go if it can't handle all your basses. Also I'd always have that "is it going to crap out tonight" thing in the back of my mind while gigging. I'm not gigging steady right now but when I do I usually carry a BU head just in case. Still though, you shouldn't have to worry about if your rig is going to act up or not. That's not acceptable especially in a gigging situation. Not to mention the fact that it makes you and your group look like amateur night if your rig pukes and you have to spend 10 or 15 minutes switching amps.

