To begin, I apoligize for my lack of fluency on the topic. I took my SVT-3 Pro to a friends house who has a moderate knowledge base on the electrical side of things so i am primarly going off my recolection of what he said. here is my setup: The SVT-3PRO I replaced all of the 12AX7s as soon as the first problem became apparent. a schecter custom 5-string diamond series with an active eq and EMG-HZs Boss TU-2 Boss GEB-7 Fulltone Fulldrive 2 MOSFET B115 acoustic cabinet About three weeks ago during my bands rehersal I noticed a huge difference in my tone, the only way I can think to describe it is "Farty" After spending time eliminating all of the variables I found that there was an issue with the GEB-7 and/or the Fulldrive 2 through the effects loop in the svt-3. After talking to my friend he told me that this is the case because both of these pedals are digital and are not ment to run in a parallel loop as presented with the effects loop. So after hearing this I ran all the pedals through the input jack in the front of the amp. When I did this the Fulldrive sounded exactly the same as it did when I put it through the efects loop and the GEB-7 seemed to only give the farty tone in the lower register of the B string. When I plug the bass directly into the amp there were no apparent problems. I am at my wits end with this stuff I am so frustrated with my newly purshased SVT-3. I have no idea were to go from here to fix the problem. ANY INFORMATION OR TIPS AT ALL would be dearly appretiated. I did my best to get all of the information up here that I thought to be relavant but I think it would be easier if someone would post their question.