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.

If it were me I would go for a good tube amp. One that is not fat sounding. That can also be caused by the tube amp / speaker combo. so make sure that the work well with each other. 

So now that you are there you can try some different preamplifiers, both tube and solid state and find out which one you prefer. 
I have been chastised for not indicating that I am a dealer and I just forgot to do that. Sorry. 
Many meaningful contributions presented.  In my experience I have discovered that finding a great preamplifier a daunting task. Let's face it, if your preamplifier can't resolve the micro-details/dynamics along with the other obvious positive qualities, you have already lost the battle. The power amplifier can't compensate for lost or inaccurate information. Seems easy enough but in reality not so much. 
In this light I would place the preamplifier as the most influential electronic component in the audio chain (limited to preamplifier & amplifier).
Remember that our passion and pursuit of our individual goals is not assisted with implemented standards by manufacturer's that helps us along our journey. 
No standard voltage requirements to drive an amplifier to full rated output and impedance issues as well. Many preamplifiers are fussy about length of Interconnects, etc.
Best of luck and happy listening!
I have tried all combination's with exception (by choice) to having both the pre and amp being tubed.

I find for low level, late night listening, a tube amp or integrated amp will sound much better than anything else for the money.

A tube preamp is useful for injecting just enough 2nd harmonic distortion to help ameliorate much of the phase issues or crossover distortion with lesser quality SS amps or Class D amps.

I found that listening DAC direct (balanced) to my class D monoblocks to be pretty much unlistenable.. grey and clinical with an over-emphasis on detail and HF transient response. However i've heard worse for much more $ at trade shows, unbelieveably.

Because of my speakers (86-89db depending on reviewer), I use a NOS VT-99 preamp with class D monoblocks. This gives a very listenable sound with a relatively low noise-floor, and i can crank it up if need be and the soundstage stays coherent and fleshed out.

I also have an older but still excellent Pass Aleph amp which may not have the detail of class D with a tube pre, but driven directly from my DAC, it (despite being only 30 watts) has a very full bodied and spatially delineated sound. It sounds organic enough, or 'real' perhaps, even more so than tube pre to Class D. This is true for most my music except for for tracks with samples of rainfall, where the individual rain drops are slightly smeared compared to Class D with my tube pre. I assume this is most likely due to the Aleph being an old amp, older technology, running in Class A, but more importantly for me, it still doubles down into 4ohms. Maybe a Pass 30.8 would be an upgrade to the old Aleph.

The tube Pre paired with the class A Aleph, sounded too soft and sinewy for my tastes. Direct from DAC was more 'right.'

I use the tube pre and class D for summer listening, and the DAC direct to Pass for winter.

One other consideration is it took me quite a lot of trial and error to find the right tubes for my pre. Maybe $3,000 invested in tubes total, but once i found the right ones i loaded up because their difference is just that great.
let me let me append all that with the answer to your Q.

The amp will give you the most tube sound. Preamp is merely seasoning (although sometimes the seasoning makes for the best soup).