no there is no rebiasing necessary. All tubes are a bit different,,,thats why you need to purchase a matched pair or quad, and so on. I spoke to one of the above mentioned tube dealers about how their tubes are trust worthy in mesa amps. I was also concerned. He said mesa tubes when you order them, you will notice they come in different color coded matched sets.. When you order them online you have no idea what color will show up at the door. Therefore any of the color coded 6l6's for example from mesa will work just fine in your amp. There is a tolerence as you see. He said that he has tested so many mesa tubes that he knows what the tolerence is, plate current???? current draw???? I dont remember exactly what he said he tested to match up to mesa specs. So any tubes you buy from any manufacture will have the correct specs for your mesa. What dougs and eurotubes do is find them and match them up to mesa specs. I own a rectoverb and I use jj 6l6's from eurotubes and I ordered a pair of SED el34's from dougs tubes just to mess around with. I also use the mesa tubes.. No need for any re-biasing... I switch them around once in a while just for something different. Just remember always to switch the bias selector on the back.. I have never had problems with any of the tubes and they all sound nice.
As for the warranty, what mesa doesnt know wont hurt you. If you must send your amp in for anything make sure youve got mesa's tubes in it. Good luck all
