Any recommendations for a new set of tubes for a 2yr old Ampeg V-4BH ? It has (4)- 6L6 power tubes and (1)-12ax7 and (1)-12au7 pre tubes Right now the power tubes are GT6L6B with a "4" rating. I'm looking for a power tube that will give me more headroom., and won't distort or breakup anywhere so early as the current "4" rating. what about pre amp tubes? Also, I like a thick,full, punchy vintage tone. thanks.