I picked up my first tube stereo, a later serial numbered (78xxx) Fisher 400 in fantastic shape, with all original Fisher tubes. Not knowing the history of the unit, I briefly set it up with Heresy 1’s just to see if it worked as advertised. It sounded great, but it will head off to Casper at Stereo Rehab in Chicago for a complete going through. Might be a silly questions, but like I said, tubes are new to me: Is there any reason to save the original fisher tubes and use new aftermarket ones? Are tubes wear items and potentially having original more/less important sonically or for originality in your opinion? My experience is with restoring cars (American Muscle and British) where correct date or original parts can be a focus with a lot of folks. I am looking forward to listening to my restored Fisher 400! Thanks!