Sound quality impact - preamp vs power amp?


So how best to deploy available funds.  Better to spend on a high end preamp or outstanding power amp?  This assumes you already have high end stuff elsewhere in system.


emergingsoul
If I didn't know better and only read some of these posts, I'd think all I had to do was get easy to drive speakers and piece things together from there. Good lord.
the whole point of high end audio is trying to eliminate the weakest link.

I disagree.  I believe the whole point is to optimize the synergy among your components & room to best connect you to the music and stir your soul.
If you match a top level preamp with a lower level amp, you will reveal all the weak points of the amp. If you match a top level amp with a lower level preamp, you will never hear the top performance of your amp. 
So I agree they are equally important because the whole point of high end audio is trying to eliminate the weakest link. 
Omg Isn’t it simple? We all know this — Start at the speaker and work upstream to the source. So logically the proper matching amp would be next. 
Speaker and amp tech may not change so often as the preamp/streamer/DAC   So my view is nail those down first.  Make sure you can return whatever you get. Happy hunting. 
Sounds like a hypothetical question to induce responses. If the OP was serious, he'd simply consider an integrated amplifier within his remaining budget. Would you put an entry-level cartridge on a high-end turntable? Which is more important when all things are important? 
The amplifier is far more important than the preamp even if it has a phono stage. Amplifiers and how they are matched to the loudspeakers can make or break a system. See what happens when you put an 8 watt SET amp with Wilson's. Some speakers require a lot of power. Without it they are lifeless. Makes no difference what preamp you are using. 
 I am in agreement with @tvad.  I would like to point out that it’s easier to get a flat impedance curve with lower impedance speakers, and  that due to that lower impedance those speakers will most likely (speakers like tvad’s Soundlabs excepted) be less sensitive.
As usual, some are answering questions that were not asked, and some are making assumptions.  However, the question as asked may be too open ended to properly address without more detail.

It sounds like the OP is saying that the system is already of good caliber all around.  In that case, a better pre or amp would really offer limited improvements, generally speaking.  If one of those were long in the tooth, or lacked a feature or connection option one wanted, that might tip the scale, as it were.


Speaker amp problems are speaker problems. Trying to solve the problem of a hard to drive speaker with an amp is a fool’s errand.

That is nonsense and plain naive. There is more to sound than whether there are "problems" associated with easy or hard to drive. Perhaps MC has never experienced wonderful amp/speaker synergy before. It’s not all about the speaker being hard or easy to drive, it’s about how beautiful is the sound that can be created. Just because a speaker can be driven easily doesn’t mean it’s going to sound good or even the same with amps of similar specs. Why on earth would my speakers sound better with a relatively low powered SET amp than a SS amp with three times the power and with the ability to double down into loads of half the impedance?

I don’t think MC has ever heard the lucid and textured midrange produced by some 300B/speaker pairings while other single-ended triodes will produce more clarity and beauty, and yet others will be richer harmonically if not as incisively quick. All with similar specs and all being paired with an "easy to drive" speaker. MC apparently subscribes to the camp that if a speaker is designed to push more power of out amp, creating louder sounds, then it must be better and will work best in all applications. If volume is all you require from your speaker then your listening priorities are light years away from mine, not to mention grossly unrefined. Perhaps when I was 13 yrs old I would have agreed with you.
op is a bit confusing, if everything else is high end then both pre and power should be of same pedigree. If funds are a limiting factor then get a better integrated amp that drives your speakers well. 
Consider speakers and power amp as one voice, so if your speakers are demanding (not only power hungry) you need the suitable poweramp, if not, then go for the better preamp.
G
So a line stage preamp is the frosting and an amp is the cake, which can be layered in so many ways.  Both vitally important.  

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The acceptable phrase is silk purse out of a sows ear. Either way its bollocks. A better preamp will be a better preamp and an improvement regardless. Speaker amp problems are speaker problems. Trying to solve the problem of a hard to drive speaker with an amp is a fool's errand. 

People asking about separates while pretending to care about cost always make me smile. If you really do care about the cost/performance ratio, in other words value, the answer is almost always an integrated. With integrateds like the Raven Reflection you have to go pretty far up the high end food chain to be looking at separates- and then you're talking $50k not the (relatively) measly $11k the integrated costs.

But the audio community has guys so spellbound buying ever more stuff, and separates do help you buy a lot more stuff. You can get mono-blocks, bi-amp, and lots and lots of power cords and interconnects. 
Equal. However, most modern amps have enough gain that they can be driven by the source components (assuming decently sensitive speakers), so a good amp only needs a passive preamp with quality input switching and volume control. So start with a good amp.

Yes, everything gets connected to the preamp but all signals eventually make their way to the speakers. The speakers are the heart of the system and have the greatest influence, especially if they’re decently efficient. 
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Pre-amp is the heart of your audio systems all the devices are connected to it except the Power Amp. If the Pre-amp is highly transparent the other pieces tend to fall into position better.

highly recommend the MP-1 from Atma-Sphere if you can cut it if not the fully Loaded MP-3 is superb.
OK, so the upshot of all this is a balanced approach.  It's counterproductive to split your funds, say, 20/80, favoring either component.  Evidently, both can have a major impact on sound.  Pre-amps can often cost a little less than power amps, particularly if the latter are expensive, so I wouldn't exceed a 40/60 split, if you're looking for a rule of thumb.
In building custom audio components I have mixed input about this.  IMO unless your speakers require a specific power amp (horn speakers don't need 200wpc, as an example), then here is my overall comments:
They both offer sonic advantages - in building a Class A hybrid power amp, I thought that it was the better of the two options.  In making a few design changes to our high end tube preamp, I am not sure what I would consider having over the other.  Putting a gun to my head, I would probably at this time look for the best power amplifier since the amp works and sounds so good with other preamps we have tested it with.  Our preamp does add beauty, soundstage dimension, and clarity in direct comparison to other preamps we have compared it to with the amplifier though.

Happy Listening - you are probably more confused now!


@three_easy_payments

“And you can easily make the counterargument that a great preamp doesn’t help if your amp is a total mismatch with your speakers”

if the amp is a mismatch, then you already had issues. you can’t make chicken soup out of chicken crap, so best start with a good preamp and upgrade things down the line when funds are there.


@riley804   

preamp .

what good does it do to get a good amp if you are going to put a crappy preamp ahead of it ?

And you can easily make the counterargument that a great preamp doesn't help if your amp is a total mismatch with your speakers.  If we go with the assumption that amp-speaker matching has already been optimized then I'd agree that the preamp will be a bigger gain.
preamp . 

what good does it do to get a good amp if you are going to put a crappy preamp ahead of it ?
I think you're sorta asking the wrong question, so I will spin it differently.  For sound quality impact it's best to find an amp that has the best synergy with your speakers - so I'd focus squarely on the amp over the preamp but not just any outstanding amp but the one that allows music to flow the best from YOUR speakers.  This may not have anything to do with spending the most you can afford....it's about finding synergy.  My speakers sound best from a tube SET topology with a bit of wattage headroom.  I could have spent 3X on a higher end push-pull amp and it wouldn't sound anywhere close as good as what I have.
Depends what you like better.

Apples or oranges.

Where's integrated, the best of both?