Spend more money on the amp or the pre-amp?

Let's say you have $800 total.  How much would you expect to spend on the Amp vs the Preamp? 50/50? 75/25?

What about if you have $400 total?  Does that change the ratio?

At that price point you'll probably be better off looking at an integrated amp, and you'll need one less pair of interconnects. 
For that kind of money, I would look for a good integrated amp.
Some really good integrated amps out there these days.

You probably don’t need to even consider separates unless your budget is more than a few grand. IMHO.

Oh, @soix beat me to it!
Integrated would be a way to go within your budget.

But if you aspire to own separates and possibly extend your budget to $1049.00, I would look at Schitt Audio's Vidar amp and Saga preamp. 

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I think there are some super value low cost amps, like Odyssey and Job 225, not sure about preamps
With $800, Maybe 50-50 but I would prefer to spend more on the preamp. At this budget, you'll have to consider an 80's classic amp and there are several in the $3-400 range like PS Audio or B&K, then I would match it with a nice Dyna PAS 3, they are extremely musical.

If it were me, I'd jump right on that PS Audio 2C+ and the Dyna PAS3 that are now on A'gon.  If Audiomart, I'd look at the Musical Design, Apt Holman or PS Audio 100 Delta and the Blair Chapman tube preamp or the other custom tube preamp - I think any of these would smoke an integrated....

With $400, definitely Integrated is the way to go.  On Audiomart there is a 300B SET int amp for $450 that would smoke everything away.  In fact, I'd probably take that over the $800 separates
The preamp come first, and it must be good, till the level you want for the all system (and more, if possible).  Then the amp, with the power y speakers need. That's my point of view and what I made on my system. 
I have been convinced for a long time that a great preamp is the heart of a system. At $800, as others have said, I would go for an integrated, but at higher price points, I don't see a hard and fast rule. The days my preamp ratio is 45:55. Some years back- when I had my first truly great preamp, the ratio was more like 60:40. That preamp was a CJ 17LS2. 
I agree with looking for a good integrated with a $800 budget.  If you want new, I'd look at the Yamaha A-S801.  6 moons gave it a very good review.  You could probably find something better sonically in the used market, but the built-in DAC on the 801 appears impressive - so a great value.

If I was looking at separates for $800, I'd probably buy a used Haffler amp that's been moded by Musical Concepts.  That will probably leave around $200 left for a pre-amp.  Might be able to find a Musical Fidelity or Creek (or other) on ebay for that.

So many directions you could go...

+1 for lou’s comment .
A good Dyna Pas3 or one of its many clones is the best buy in all of audio.
Truth be told , a rational person(leaves me out) will never need more.

Also true the new Yamaha integrateds , even the lowest , are great sounding and great buys .
$800.00 get some very cheap stuff and pretend it sounds good.Good luck with that one!!

"$800.00 get some very cheap stuff and pretend it sounds good.Good luck with that one!!"

I disagree. The OP can get a very decent used integrated amplifier for $800. There's a Creek Evolution 50A for sale right now on A'gon asking $699 and I've heard it paired with Wharfsdale monitors and it sounded excellent.

I would go on ebay and buy a nicely maintained Japanese receiver from the 1970s such as Sansui, Kenwood, Pioneer etc.
As an additional comment to my post above, for $800, I'd also highly consider one of those Chinese integrated tube amps.  Audio Space, Antique Sound Labs, Jolida, Prima Luna - there's a lot to choose from on the internet.  I'd also consider a custom tube integrated as well....I much prefer tubes over solid state, so I would get any of these over the Creek, Yamaha or any other SS integrated in this price range.
Yes, i agree with the suggestion to find a vintage Japanese integrated amp/preamp//tuner.   The higher power Pioneers my favorite.
But for $800 make sure that 40+ year old vintage piece has been truly refurbished not just cleaned 
Nakamichi CA5 < $300 and PA5 < $500, can't think of any integrated < $800 can beat that combo
It depends. Do you you need a phono stage, tape loops, HT pass through, how many line level inputs.? Perhaps more importantly, how much power into what kind of impedance load do your speakers need in your room? Depending on the the answers to the above, you might find some power amps that are suitable for use with some fairly inexpensive passive pres.
Mostly great suggestions, but I would advise caution shopping for used or vintage equipment unless you are prepared to work on it yourself or pay a technician $85.00 an hour.  At the OP's price point, paying for repairs or upgrades is probably not an option.
Seems strange to say this on Audiogon's forum.  This is actually a great place to buy used equipment, as most sellers are audiophiles themselves and know the value and condition of what they are selling.  You will usually find good, fair deals.  When shopping on the open market, however, caveat emptor.

I bought a Rotel RB-1552 MkII here for $300. It is dented on the top but sonically it is perfect. If you keep your eyes peeled and stay patient you can find great gear. The DC offset on mine is so low it's hard to measure, and it is quality gear. That would leave $500 for a preamp and you have a lot of options at that price point. If we knew more about your source and speakers we could recommend something more specific. Do you prefer tube or SS sound?

If I'm not mistaken group, (leemaze) was using $800 dollars as a nominal figure, a hypothetical to obtain a ratio, not an actual amount for his budget, - eg: 50/50 or 75/25.

Still "leemaze" my experience would have to say .... it depends.

 Are you going analog, or digital? Vinyl IMHO is more pre-amp dependant than digital.

If you have efficient speakers (eg: Klipsch Horns) that are easy to drive, a good clean high current amp is all you need, so your bias can weigh towards spending more on a snob pre-amp to obtain that desired sonic signature.

On the other hand if you are using a low impedance speaker (eg: Martin Logan Monoliths 4‎Ω-2‎Ω), you're going to have to take care when it comes to the amplifier you select, so the ratio will tilt more towards amplifier selection.

 To provide a loose rule of thump for you, if you have an analog set-up that is, or borders on esoteric (separate tonearm & cartridge), my experience would roughly be 55% - 65% of your budget should be towards your pre-amp ( TUBE Pre-amp .... if going that way, tubes should be factored separately).

Hope that helps.

Hi thehorn,

yes, exactly - this was meant to be a more theoretical/academic than applied question. Your insight is interesting and seems to make sense. It is interesting to hear that many folks find an integrated amp to be the best value at those price points. Because I’ve heard elsewhere that "separates are always better".

Concerning my system(s) specifically, I listen to CDs and google play streaming Via airport express airplay.

system 1:
KEF Q Compact speakers
NAD 304 integrated (just got the audioquest interconnects)
Rega Planet CD player

system 2
Wharfdale Diamond 10.7 speakers
Marantz PM6005 integrated
Marantz CD5004

I was thinking about purchasing an amp to pair with the NAD, but I’m not sure I love the NAD - it sounds pretty muddy/bass heavy with the KEFs. Would a higher powered amp clean up this sound?
I do agree with thehorn's position regarding the theoretical side. The amplifier/speaker match is critical to best performance.

Though years back separates were considered better than integrateds, these days that comparison does not always hold true. Especially considering the more modest high end systems, as are your 2 systems.
Regarding your system 1, I would take your speakers and your 304 to a dealership and compare with different integrateds/amplifiers. Best way to hear for yourself.  That said, the character of a system can be altered to a greater extent with a change of speakers than the amplification.    
Reading through this thread, I realize that $800 is exactly what I spent on the pre and power amp in my living room system. $450 for a heavily upgraded AES (Cary) AE-3 tube preamp and $350 for an Adcom GRA-5500. Both used, of course. So for me, about 56/44.

Of course, after buying upgraded tubes and getting the preamp tube sockets repaired, the cost for the preamp was greater. :-)

Not sure what your audio approach philosophy is here "lemaze", but I can tell you this, go after two rabbits at the same time - you'll wind up with neither one. In other words 1 good system is better than two mediocre.

 At any rate it seems that (system one) is what you're trying to optimize at the moment, and I'll speculate that the Kef Q's are being used because the room is small. (the room is an intricate part of your system). A canon will never sound good going off in a phone booth, inversely a pop gun won't get it done in an open field. Synopsis: optimize your room.

 Secondly .... the NAD has to go - period.

I've been using separates since 1980, a NAD was my 1st pre-amp. Twelve years later I started A/B-ing multiple pre-amps at a time in my listening room, the NAD went to the curb. NAD's are entry level Hi-Fi, they are chinky, grainy & bright in comparison to what's out there. It's time to move up.

 Since 1980, some of the most pleasing systems I've heard used Integrated Amps. So although I use separates I would not "DIS" Integrateds. Although the Kef's are small, they are only 89db efficient, so a strong hand will reproduce the music with more authority, better circuitry will render more intricacy, clarity, and a lower noise floor.

 May I suggest (used) a Classe' Audio CAP-151, a Krell KAV 300i, or 400xi, a Bryston B100, and I strongly recommend giving the Rogue Audio Cronus Magnum II with the KT 120 tubes an audition. http://www.enjoythemusic.com/magazine/equipment/0816/Rogue_Audio_Cronus_Magnum_II_Stereo_Integrated_...

 Anyone of these Integrated Amps should mate up with your Rega Cd player very nicely. Over kill? Not if you consider that you can swap the amp with system two, that you`ve now opened the door to actual Hi-Fi, closed the door on Mid-Fi, and can now use virtually any speaker you want.

Hope that helps.

Thank you for your thoughts thehorn!  Much appreciated. 

Though I cannot afford the jump from the NAD ($120, Craigslist) to a $1000 integrated tube amp. Though I will certainly keep those options in mind. :)

I'm more interested in the best possible "mid-fi" I suppose. 

I love the KEFs and they seem to be suited to my room (10'x15'). But I have the bass turned halfway down on the NAD and they still sound a little muddy sometimes. 

Another thought I had was to use the NAD as the amp and get the best sounding $200 preamp I could find. 
OK lemaze .... here's another suggestion.
Use the volume control on your Rega & run it straight through an amp.
For $200-$300 dollars you can pick up a used Carver M400, or a David Hafler DH-200.
An audio steel @ twice the price & both will put the NAD to shame.
I still have an M400 on the shelf, even though I've been using a Classe' DR9 for 10-12 years.
I've kept it as a back up for when I ship the DR9 back to Classe' Audio to get recaped.
Agree with those who say "integrated" and add a further wrinkle:

The more efficient and sensitive your speakers are, the better a cheap amp is going to sound.  People with K-horns report great results from TPA3116 chip amp boards (which have volume controls); I've paired one with some 91db/1watt Dahlquist DQM 9s and while the sound could obviously be improved on, the results are super suggestive of what could be achieved in this manner.

You stereo is a system; build it like one.

I would speak to your local dealer and visit him. He will treat you with respect and even more respect your budget whatever that may be. Build your systems with respect. Happy listening my friend.

IMHO, the "separates are always better" mantra is at least 30 years out of date. Two advantages: 
Value for money: you're not paying for interconnects, another power cord, another chassis, and more packaging (it's amazing how much the latter two account for the wholesale price, especially at lower price levels). 
Performance: I believe that lot of what makes a system more "alive"-sounding comes from lowering the noise floor. Bad grounding and impedance mis-matches play havoc here; an integrated eliminates pre/power interaction problems by construction. 
Advantages of separates include automatically separate power supplies and easier shielding, but in my experience skilled designers can now make integrateds competitive with separates at prices well into five figures.

Update for anyone interested:

Got a Rega Brio-R off Ebay ($430) for the KEFs.  Sounds fantastic.

Got a NAD 7175PE off Audiomart ($170) for the Wharfdales - sounds really great.

Thanks everyone for all the thoughts and ideas - really helped me to sort through things.
Congratulations. Thanks for letting us know what you chose. Fill us in with some details once you've had time to evaluate.
Sounds like you did well. However, I still want to make a suggestion with respect to the orginal question: how about the new Yamaha RN803d receiver? It is 2x100 watt rms at 8 Ohm, has digital inputs, Spotify Connect Airplay, networking capability and much more. And it has room equalization capability.