McIntosh tube upgrade - worthwhile?

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. ..

Tubes from different manufacturers each have a unique sound but the differences can be subtle and will be obvious to a careful listener when the audio equipment is high-end  

Tube swapping is very noticeable on high end equipment to a careful listener.