I had my Deluxe Reverb converted back to 6V6s from 5881s and returned it to it's original bias circuit. The shop it was done in didn't have a functioning bias probe. So I took the amp home and biased the amp by turning the amp on and monitoring the tubes as I adjusted the pot and using a guitar to monitor the sound. I'm guessing this isn't the recommended method, but the amp came out sound better then ever. I was told I can go back whenever I want to get it biased with a probe when the shop gets it probe working again, but should I bother?