McIntosh tube upgrade - worthwhile?

+1 for Brent Jessee, huge selection of hard to find tubes. He's not giving them away, but he does have a 30 return policy (with restocking fee), and he does warrant his tubes against failure for 30 days. I've had great experiences with him for 12AU7 family, 6SN7, rectifiers, and power tubes. I've found him to be honest in his recommendations (sometimes preferring a less expensive tube), and he understands which tubes might work better with certain equipment

As a reminder this thread is about whether tubes on a Macintosh amp makes sense to change.

It's not a marketing opportunity to sell tubes.

It may turn out that it doesn't really matter what tubes you use in a McIntosh amplifier.  The amplifier sounds pretty darn good with the JJ stock tubes but could it sound better with different tubes? That's all

Well, thanks to all-ya-all it did turn out to be an opportunity to sell tubes. I called Brent and have 4 new tubes on the way! Thanks guys!

@emergingsoul 

Posters were giving you additional advice on where the buy quality tubes. That was an opportunity to show gratitude. In that spirit, Brent is very good, but I think Vintage Tube Services with Andy Bowman is superior. Andy knows more about tubes than any of the sellers and is more thorough testing. Andy or Brent is a win. 

Pat Hickman, Oregon, knows more about Mac amps than anyone I've ever met. He would be able to answer your question. What amp are you using? What improvement are you wanting to hear? 

The Mac I own sound great with the tube that it came with.With the prices of tunes now, no thanks....I'm on a fixed income now at 72.And need new a new heating and cooling system NOW. ..