Been listening to the WE 422a and 5998's with stock EH drivers. Getting the treble extension and sparkle I desire plus overall 3D staging via Utopia's. The 60 hz hum in signal chain is louder though. Wondering if the larger 5998's are contributing to that. Also concerned about rolling a higher gain driver like ecc32 contributing more noise. If I could keep current SQ with a silent background, WA22 would be my forever amp. ...until the next one.