But will it be compromised? I have a matched set of 6V6GT tubes that were in my 1970 SF Deluxe Reverb Amp. They are one gray smoked bottle RCA 6V6GT and an older EH 6V6GT, they were biased at 417 PV @ both are @ 26ma in my Deluxe. I have a new amp that came with JJ 6V6 tubes that the manufacturer says are biased at 26ma. I replaced the JJ's which generally I've never liked, with my known matched pair and the amp really sounds much better to my ear. Can this cause problems in my new amp? I don't want to reveal at this time what my new amp is. Thanks.