the funny thing is actually that my eden wt-400 head was & is working properly. thanks for everyone's help!! a funny thing happened last nite with my eden head: i just received my 55-02 (lovely, lovely!!) and plugged it in. as per eden's advice, i turned the post gain all the way down and turned up the pre gain looking for the compressor lite to flash (thus finding the "sweet" spot). but, the lite never came on! i dis-engaged the compressor, but the set level lite never came on. i turned up the post gain a little. i was getting signal thru the amp, but i found that the pre gain (with or without the comp) increased the volume only up to the 12 o'clock position. after that, the knob turns up but the signal remains the same. this happened with or without the active pre on the bass engaged and with or without the "active bass" pad engaged on the amp. all combinations tried. the amp is 4 yearsd old, gigged regularly, and never opened or cleaned or tube replaced. there is currently a thread here with stories of woe about screws shredding and stripping upon turning that has me a little nervous. i called "eden." when i first got the amp, david answered the phone. this time i got the general rep guy. he is very nice, but couldn't troubleshoot the amp and told me that there is no real talk-to-the-eden-techs opportunity anymore. could this be as simple as a burned out led? would i get sound (pretty loud) if the tube died? any help would be appreciated since you guys appear to now be my best bet for eden customer support! p.s. other weird thing: i got the grounding buzz also. it would go away if i 1) touched anything metal on the bass 2) dis-engaged the active pre on the bass 3) turned the pup pan all the way to the humbucker side (active pre engaged).