For tube sound, which is more important: preamp or power amp?


I have always loved the “tube sound” - warmth, midrange, soundstage. Through the years (since about 1975), I have owned many tube and solid state amps and preamps, in various combinations. Presently, I have a tube amp and a solid state preamp. But like most of you, I am thinking of making changes, again.  Not to cloud the discussion, the specific brands are not important.  I also listen to acoustic music, females vocals, love mini monitors, EL34s, NOS tubes, and don’t care that much about bass.  So you can see that my taste fits the tube sound very well. But I have had systems that are too warm, not enough dynamics or details, and fat in the low end, too.

okay, now to the discussion.  To produce the tube sound, which is more important: the preamp or the power amp?  Let’s talk in general, and (if possible? May not be) not tied to one specific piece/brand/model of equipment.  I know there are exceptions to any general rule.  Not sure if it makes a difference to your comments, but I have no phono and am running line stage only.

As an attempt to prevent the conversation as going in a big tangent, let’s assume equality of price/quality. i.e. not comparing a $10k power amps contribution to a system to that of a $1k preamp.  Let’s also assume that the amp (tube or solid state) can drive the speakers just fine, such that compatibility does not limit the decision. And ignore mono blocks versus stereo amp differences.  

two follow ons: I have  the perception that preamps give you more bang for the buck - meaning that it takes less money to get a great tube preamp compared to a great tube amp.  Agree/disagree? And second, I have never owned a tube dac or CD player, and will assume that tubes in either of these is less critical than in a preamp or power amp. Agree/disagree?

i am interested in your thoughts.

Bill
meiatflask
Very late to this party but an interesting read.   Which is more important? I could not figure that out so I bought a Raven Integrated Reflection MK2 tube amp that right now generates around 65wpc.  Having an integrated tube amp provides me everything that I want and I could not be happier with the power, performance and the sound.  I also like that I am able to play with tubes.  I have 4 power tubes.  I have tried 6500's, Vintage GE, KT 88 and now KT 150's.  You do get slightly different sound with each one.  I also have 12aT7's, 12AU7's, and 6922's.  I like the convenience of one component as opposed to two.  It is a showcase piece and everyone who comes into my house wants to know what it is.  
I agree with mofimadness. The preamp will give u the tone u want; the power amp will amplify that sound. IMO, u can't have a power amp that's too powerful. Class A bias is the way to go, if u can swing it. 600-1200 watts is good, depending on your speaker efficiency. U want something u can weld with. No clipping; good tight bass. Tube preamps👍  Some tube preamps have a bit of tube rush. They require low noise matched tubes. If you're in to quiet classical music, they may not be for u. 
I have been using a Conrad Johnson PV9a pre into a Quad 306 Solid State to drive my B&W DM70’s.
The speakers are a Hybrid Electrostatic that are not the easiest to drive, so I thought that this would be the best combination.
In fact it sounded great and gave great pleasure.

However just recently I got hold of an Art Audio Quintet power amp.
This has taken the system up to a whole new level.
The soundstage has opened up and the sound is much more dynamic.

These particular power amps allow switching from Triode mode to Ultralinear plus feedback switching (.5 to 6 db I think).
I now find that I prefer Triode mode and minimal feedback whatever music is being played.
Is it possible that one of the reasons that Valve amps sound so good is that they tend to use much lower amounts of feedback that most transistor amps?
I have noticed that the sound seems to open out as I select lower amounts of feedback.

Anyhow, I am shocked as to how well these amps drive my B&W’s even in triode mode with just 15 watts.
I would not want to go back to using a transistor power amp on my main system.
If I did upgrade in the future, it may be to a single ended triode, but for now I am more than happy.


Iscm,
As the level of negative feedback (NFB) is increased the output impedance decreases and damping factor (DF) is increased. Depending on the speakers involved the additional NFB can be beneficial up to a certain point. Generally speaking I believe that the less NFB utilized he more natural and open the sound quality becomes so I understand your listening observations. Some speakers are intentionally designed to work very well with low and even zero NFB amplifiers.

I use a DAC, line stage and power amplifier and all 3 of them are zero NFB designs. The result is a very organic, lively and emotionally engaging sonic character.
Charles
I went all tube- pre, amp, phono - more than 30 years ago, when SS amps were harsh and consequently, I had lost interest in recorded music.  Solved that problem!  Amps and preamps are equally important.
As many above have noted, there are many ways to skin a cat.
   I think tube maintenance issues are exagerated. Yes you have to change them every few years, and they cost a bit.  It’s trivial compared to what most here have spent on gear.  We all have had to nurture some trouble shooting skills, and occasionally, soldering. No big deal.
   You can make an argument for ss amps based on less heat and power useage, and sometimes these can be controlling factors; I live in Houston, there are times I am not inclined to run all those tubes - but I’m not convinced that class D amps will compare.  the electric bill (power and a/c costs) is a relatively minor consideration when you’ve spent tens of thousands on gear and content.
  Tubes are more musical.  I really see no reason to use a SS pre.