Another amateur in need of advice

Why not if the OP likes Quads ? Only I would get Rega P6 with Exact MM cartridge and next in line Rega integrated with phono. That would be about $1700 more, that's $5600 without cables and power cords.

I'll throw out my anecdotes FWTW.

• Component allocation: I agree with some others that a large portion should go toward speakers. They contribute the greatest amount of distortion by far - that's a fact, therefore you'll want good ones. This isn't to say you want speakers with the most impressive specs on paper - such specs are often meaningless.
  

• Turntables: I think you've picked a good one. ~$1500 is where turntables really begin to shine. The MoFi and Technics 1200GR are probably the best current offerings in that range.
  

• Integrateds: I agree with others that it should possibly account for the smallest slice of your budget. There are many great budget integrateds out there right now. IME however, the Sphinx V2 is not one of them - not because of noise floor, but because it produces very weak bass at lower volumes. My local Rogue dealer agrees. The Yamaha A-S801 is better and fewer $$$. A used Exposure is also a good recommendation. I haven't heard it but the Outlaw RR2160 is an intriguing piece that measures well and seems to have many satisfied owners.
  

• Phono preamps: don't underestimate the importance of a good phono preamp. I've owned the Lounge LCR, and while it's good for the price there is much better performance to be had. Since analog will be your primary medium (or you think it will), I would at least get the LCR Gold or the LCR with Robert's factory upgrades (probably just have to call him about those). I was very skeptical of the importance of the phono preamp until I leaped beyond entry-level units. That MoFi package should be very well deserving of a $700^ preamp.
  

• KEF LS50s: They are not bright speakers - not anywhere near as bright as the typical B&W, Revel, or Focal speaker. I think those who claim they're bright are pairing them with subpar electronics and/or using excessive toe-in. KEF also recommends 24" stands which place them below ear height for most listeners. IME, when placed properly, they're actually about as warm as you're likely to find in modern speakers, aside from a very slight metallic overtone (as is the case with 95% of metal drivers). Most are probably using them with suboptimal placement. Until I got a pair of Tannoy XT6Fs, the LS50s were my favorite speakers under ~$3K. The $1500 Tannoys (with average dealer discount) now top my list of best budget speakers - which includes the likes of Vandy 1Cis, Magnepan 1.7s, and MA Silver 200s. This isn't to claim they're the best value out there, but the best value out of the many models I have experience with. They offer many of the LS50 strengths, but with greater bass depth and output, and none of the metallic overtone. The Tannoys also manage to produce good dynamics at moderate volumes, which is pretty rare among modern speakers in general. 

 

It depends on if your vinyl is new pressings of newer music or vintage or repressed older music.  During late 1980s the common media to the public shifted from 'records' to CDs.  During that crossover period, many sound engineers where thinking vinyl and it was pressed on CD and sounded horrible.  The frequency distribution and dynamic range of CD and vinyl even from the same mastered originals are quite different.  Also, once when you're over 40 your ability to hear cymbals and higher pitches declines preciptously.  I have auditioned CD and vinyl of the same consumer-available source material, as just purchased new pressings of each in blind hearing tests for audio people aged from 15 to 50.  EVERYONE knows the difference between a CD and vinyl, blindfolded, at reference volume.  However, vinyl people say vinyl feels warmer. CD is more 'accurate' and dynamic and 'cleaner', but maybe too bright.

For some bad news.  In your price target range, you simply won't get today's version of audiophile.  You can get decent 'home quality' if you follow all the advice above in the postings.  But you won't even get prosumer or enthusiast.  'Audiophile' is very expensive today because manufacturers have been raising their prices over time, and especially over the past ten years for some equipment that essentially is the same schematic, they've just added some digital capabilities.  Copper has gotten alot more expensive and they're the green people who want hi-fi as class D, instead of A, or A/AB.  I would suggest stay in the AB world.  'A' on its own isn't powerful enough except for boutique applications and D is really the same as the arguments about 'high current' amps, etc.  These are excuses to not use more expensive raw ingredients, but rather high R&D to simulate the former when there are extremely popular amp designs that enthusiasts love, but they don't make any longer as an industry.  Try to buy a 'quart' of ice cream made with 'milk' and 'cream' and 'sugar' at a grocery store if you need empirical evidence.

Back to the question....What was also not presented was that if you're using vinyl, most vinyl sounds best on its second or third play.  The first play gets some of the microscopic manufacturing debris out.  Enthusiasts and audiophiles when 'records' were the main source, would immediately re-record albums to tape or reel-to-reel and when only in the mood, listen to the vinyl.  It's in inherently destructive media.  You ruin the record every time you play it.  Despite balancing techniques on the tone-arm, gravity still exerts force in the groove.

Also, you need a very good quality album cleaner, like $500, wet cleaner.  Buy anti-static sleeves and store your vinyl upright.  Upgrade the stock cartridge of whatever record player you buy.  It would not spend more than $500 on that (turntable and upgraded cartridge/needle..so $350 on the turn-table and $150 on the thing on the end of the tone-arm), but make sure its __direct drive__ and use a smartphone app or get one old-school-style that you can monitor the RPM speed via strobe.

Keep in mind, at louder volumes, you're going to hear the ssssh, ssssh, sssh of the media.  It's unavoidable.  Avoid 'pop's' using religious cleaning before playing each 'record' each time.  No one's mentioned wow or flutter and also if the vinyl isn't PERFECTLY flat....don't play it.  Put it in a frame, on the wall, but get another new or used copy from a new trusted source.

Speakers are a matter of taste, but physics is physics.  Speakers push air.  Speakers waste 90% of the electrical energy as heat.  Do not buy exotic manga, low ohm, electrostatic, whatevers if you're not used to them already.  Basically if you need to plug a speaker into an outlet, don't get it.  Based upon your room specs you should get floorstanding 2 or 3-way speakers that have some decent mass (like 40 lbs each) to get decent bass.  Also, __placement__ is a big deal as well.

Now I've spent around $1000 of your $5000 (record player, cleaner, accessories), less $2500 or so on hefty speakers of your choice, not gimmick satellites that you need to sit perfectly in front of to get the bass and treble respond they report.  Some will argue bass is non-directional as a knee jerk.  It is true for ambient noise, unwanted noise, sound reinforcement, etc.  As far as feeling the thump of bass drums and guitar, there is more than 'frequency' to that and its recreation than arguments about non-directional bass.  For live concerts, stand on the floor for part of the concert and then go in the stands.  Now tell me 'bass' as insomuch rather than test-tones is non-directional.  Your chest will feel it differently.  Speakers push air.  Bigger speakers push more air.

You've got $1500 left at this point.   Do not buy fancy wires or interconnects.  Use fairly short distances of a reasonable thick gauge wire and make sure they are attached well at the endpoints.  Do not fall prey to 'yes but its a high current amp'.  Electricity is electricity and you are using something that uses capacitive resistive elements.  Salespeople turn up high current amp gain levels to really high numbers and scream over the noise 'see, its just as loud as those other systems'.  You want power reserves and room to dial-in the volume level you want.  Get something that will sound decent at volume 3 or 4 (or 10).  If it needs setting 7,8, 9 or 10 to get musical, move on.  Get a vintage __receiver__ of 100 watts or more that has been recapped and/or refurbished by a professional or get a re-issue two-channel system from some of the bigger Japanese names.  You can always get a professional to re-hab a receiver for you for $500 or so.  Don't get anything made in the 1980's.  Either late 1960's, any 1970's or earlier than 1995 but not 1980 anything.  During the 'power wars' of the 1970's there were many brands that are not-so-great now, but they were very-great then power-houses.  You want a receiver that weighs 30 lbs or more because you want large capacitors, a solid chassis and a very heavy power supply....the more copper the better.

You, my friend also need something with a 'loudness' feature because you want to listen at loud and soft levels and get a decent experience either way.  That's the catch-term feature that will do it.  Modern receivers and pre-amps usually do NOT have these feature.  Also, do not try to over-engineer your system on specs and sound levels or noise levels.  Nothing has been invented since the invention of the transistor and its basic application as a sound amplifier that makes any amplifier of today so so so much better than what was sold 30, 40 or 50 years ago.  You just need to refresh old capacitors.  They dry out and die but are relatively cheap to replace.  Every year, you get marketing that everything is the newest and best its ever been.  That's simply not true.  For example, a well-maintained McIntosh system from the 1960's or even 1990's bought in 'todays' dollars will be on par with any new system if you adjust for hearing loss and dollar ego.  Also, every amp version and 'brand' has a different color according to the designer because a truly 'perfect' amp would sound horrible.

Good luck and spend the extra money I saved you on lots and lots of new and used 'records'.  Also, go find some real-life vinyl people by going to a vintage vinyl store and talk to the owner or clerks and ask them what vinyl sounds best on.  They probably have a pretty decent setup in the stores they can show you.  They just don't have the 'new' version of it sitting in boxes.  I know they will not blurt out go buy a newer design NAD amp, etc.  It's just part of the adventure.

Having dealt professionally with music for 30 years I will challenge one of the previous posts. The biggest mistake you can make is NOT Spending enough on speakers ! The final quality of what you hear depends more than 90% on those components that transform the  signal back and forth form electrical to mechanical / digital. Hence speakers first and cartridge and DAC second. Any competent amplifier / cable combo will do. Take this to the extreme, try it out. Build a system with a 400 $ amp and a 4.000 & speakers; then do the opposite, 400 & speakers and 4.000 dollars amp. Do you hear any difference ? Which one sounds better ? Any dealer will be able to help you with that test.

I want to add to my previous post. I truly believe the industry as a whole is forcing us, the users, to over weight the importance of electronics. How often do you change electronics and how often do you change speakers ? Electronics of far easier to deal with / sell / buy / exchange. Speakers are not, they are bulky. But sound quality depends 90% on them IMHO.