Component percentages (Excluding cables)

The question you are asking really only pertains to one and done- and even then more as a guide. Because far too many people make the mistake of thinking in terms of speakers and amp, forgetting all the other equally essential components. 

When building a system starting from zero and for someone who really just wants to be done and happy, then the best approach is to budget equal amounts. Because, contrary to what you seem to think, every component is equally important. Since the components are something like source, amp, speakers, and wire/tweaks/accessories its an easy 25% each. This works great as long as you realize that as the budget increases you are able to expand tweaks/accessories to include things like power conditioners. 

But while that was your question its probably not what you meant. It makes no sense for the typical guy with an existing system to think this way. Especially not if he has long term plans of continual improvement. In that case it makes more sense to look critically at each component in light of the whole system and those long term plans. This may mean at some point going much further with one or more than would make sense for one and done. 

My system for example has an analog front end that if priced in terms of new equivalent would be greater than everything but the tweaks. Yes the tweaks add up to more than the amp. More than the speakers. More than everything except the analog front end. The tone arm alone cost more than the speakers I just bought. Which cost less than the speakers that came before. Which is why talk of proportions makes little sense except in the case of one and done. And even then taken not to be taken literally. 

Here are the percentages I wound up with, factoring in the cost of NOS tubes and a relatively reasonable power setup (cables, surge bar, etc.).

Because I sought out deals on used and open box items, some final percentages here might be different than they would have been if I had paid MSRP.

37% Speakers (main and 1 sub)
33% Tube Amplification including NOS Tubes 
16% Sources (CD transport, Streamer, DAC, tube for DAC) 
14% Cables/interconnects/power 

millercarbon, thank you for such a thoughtful and detailed reply. You really gave me a lot to think about, and I understand where you're coming from. Thanks again.

Thanks hilde. Bonus question: as you've moved up the food chain, what changes to your system do you think would have the greatest impact on its current state? For example as I got into better gear, I noticed diminishing returns from my DAC choices, and a much greater return from having a better preamp stage. Or, I found that even good class D amps, which were the stars of my system for a while, were imparting a sameness to the output when I upgraded speakers, which went away when I invested in better class AB. This sort of goes back to Miller's point, that there might not be a specific ratio per se. I guess looking at my ratios helps me at least have a rough road map for where I might be able to unlock greater performance, even if it's not a perfect system.

Bottom line : I'm an audiophile, and it's wonderful. 

@Wassaicwill

My streamer is the weakest link but I'm reluctant to do much there, yet.

My DAC, the Orchid MHDT has a nice Tesla tube in it and is R2R design. I guess it could be improved upon, but it seems like it will hold me for a while.

The next thing I'll probably do is improve the output tubes in my Quicksilver Mono 60 amp. The tubes in there are JJKT88's (about $48 each) but there are others with a different sound signature I might like to try.

Down the road, I'd likely add another sub. I have one now.

Also: acoustic analyses of my listening space to address some reflections and nulls/peaks.