Bought an used Spider IV 75. Amp would cut out and was noisy. The amp did not like high volume input from guitar. Particularly with humbucker guitars. If I set guitar volume at ~4 or less (general estimate) it appears to work fine. Above that, amp is erratic. Hope this helps someone having this issue. Could be a fix for other solid state amps with this issue.
The FBV EXPRESS MKII volume and wah will not work with USB pluged in to the FBV EXPRESS MKII... Need only the Plugin from peddle to amp (or POD or what ever)... This is mentioned in the FBV EXPRESS MKII manual...