Amplifier Power tubes - important to sound?

@mulveling 

Yes I am looking for siemens 6550. It does look elusive.  And will have to revisit the source of recommendation whom is very good at what he does. I like to biamp so I'm using MC 901 monos from McIntosh.  I like them a lot and they blend tube and solid state very nicely.

I do like VAC quite a bit and still think about it. 

Curious, I read herein that the feedback level related to the amplifier is important to consider for purposes of evaluating whether it really makes much of a difference to tube roll power tubes. Anyone know why that would be?

Further, I am biamping with mc 901 monos and since the solid state part of it handles the bass drivers maybe power tubes are not that important since it appears it impacts the bass area more so.

But since I love spending so much money on everything audio even the slightest change might be worth considering. Maybe power tubes would impact the mid driver.

There are some people posting herein who know a hell of a lot about tubes. It’s actually kind of scary.

Do power tubes affect the full freq spectrum or is it more focused on below 250 hz?

@mulveling 

Maybe I should’ve said do they impact the lower frequencies more? You own interesting speakers

@mulveling 

Interesting reply, thank you.  Along with incredible knowledge about tubes, you also must have incredible hearing sensitivity.  You conveyed you listen to your music very loud I hope you are appreciative of the likelihood the sensitivity will diminish rather quickly overtime. Or maybe not.

I guess since I'm using an MC 901 amplifier, changing the smaller tubes made sense, but because the solid state section of amplifier focuses on 350 and below maybe new Power tubes to replace whatever the heck is used for the stock tubes which I think is JJ may not be that meaningful. However it appears they do impact upper frequencies in a meaningful way so probably Worth doing.

I keep in mind that there is considerable value in higher priced NOS tubes because presumably they will last a heck of a lot longer, sound a lot better and hopefully the quality will hold up better overtime.

My thoughtful niece tells me that having Alzheimer’s can lead to a wonderful experience of being able to watch really great movies over and over again.

Of course when she drops me off in the middle of nowhere or in a shopping mall I wonder why.

Or a way to justify them installing mediocre tubes with their amplifiers. Somehow commentary in manual does them less good service because having the ability to modify sound using different tubes is an important feature and why someone buys a tube amplifier.

What did they do that prevents a tube character from coming through? Is this a good thing?

I'm sure Jesse does. This is the greatest place to buy tubes in the entire whole wide world