Where did you sink the most cash into?

I'm not interested in how much anyone  spent, but I'm curious what the single most costly item in your system is- ie, amplifier, CD player, etc.

I will go first- in my present set up, it's speakers. 

But I can't live without my ancient Zerostat (the red one) which was probably 1/3 if what they retail for now. My most enduring audio purchase!  
Amp, source, (speaker and pre =tie), power cond, cables.
Speakers and amps, preamp, sources, cabling, power cond, and power cords. 
My music collection! LP's, 7" 45's, CD's/SACD's, tapes. Somewhere around 10,000 of them.
Speakers - IA/Pre/Pro source - cables - room treatments
Lots of cool stuff.

Cash percentage:

60% - electronic noise reduction devices/noise-reducing power cords.

12% - cdp

11% - 3 amps (no pre-amp)

12% - speakers

04% - passive subs

01% - spkr wire/IC’s

00% - room treatments (nothing other than furniture...so far...)

Yup, the "tweaks" cost more than the system, but wouldn’t have it any other way at this point.

In descending order - Cables, Speakers, Turntable, Amp, Phono Stage, DAC, Tweaks & Treatments.

Music is in there somewhere, but I can even to begin to assess what it's cost.

What  fun ride it is :-)

Based on prices when new:  Speakers 30%; Amp 30%

Based on prices actually paid:  Speakers 40%; Preamp/Processor/DAC (one component) 20%

-- Al
CD collection.
My Silverline Boleros represent about 50% of the value of my audio system, excepting my music collection of course. 

Very nice speakers, BTW. :-)
I'm old school & was always taught & truly believe to spend 50%-60% of total budget on speakers - of course back then all you needed was speakers, a receiver, turntable & cassette deck for a system.
I still believe in spending about half your budget on speakers, then amp/s, pre, phono, cartridge, cd/sacd & cables.
It has always worked for me as no matter what source you select it will be heard from your speakers.
Most of my cash is in music.
Only 10% or less in equipment.
I started collecting records as a teenager. In looking at my collection, without a doubt, the music collection would cost more than my stereo system by far. Original Blue Notes, Six-eye Columbia's, Original Contemporary's, Riversides, Roost's, Pacific Jazz ... and then there's the classical ... 
Speakers, analog, amp, digital, cables. But the system also sounded great when it was analog, amp, digital, speakers, cables. I don't really think about where a component falls dollar wise in the system.  I just buy what sounds good.  But I do think that if you like analog, you can really hear where the money went when you upgrade the front end. IMO. 
"Most of my cash is in music.
Only 10% or less in equipment."

Lots of bang for the buck then it would seem.  Well done!
Ever notice that really good systems are often accompanied by lots of software?   Records, CDs, what have you.   Its usually a pretty good practical indicator of whether things  worked out well or not. 
Cables ➡️ Speakers  ➡️ Components ➡️ Media ➡️ Tweaks
So much buying selling trading and flipping I have no actual idea what I truly paid for anything. The only piece of my system that I straight out bought would be my dac when my cd player died, I know I spent $1250 on that no clue on anything else. By retail my speakers are by far the most expensive, but again they were obtained via trade.
  Source, amps, cabling, speakers.  Could only guess at the value of the media.
Leaving music out of it, definitely amp and pre. However, speakers come second on my list of desired upgrades. I'm looking at balanced power first.
My Room 

Good Listening


Turntable/tonearm. Spending 50% on speakers is not old school, it is only one of popular approaches. Old school is to creatively and individually approach the subject but never have a weak source.
Cabling should equal 10-20% of total system cost!
When I started out the conventional wisdom was 50% on speakers! And with my first system, all of $400- a $75 turntable, a $125 receiver, were complimented by $200 speakers! 
IMO, it used to be that the loudspeakers took a bigger percentage of a system's budget because good speakers cost more relative to the source and electronics that what you can get now. Loudspeaker research has really paid off, as it costs relatively little to get pretty darn good ones now, don't ya think?
Based on msrp, once my system is complete, this is the order in which I will have spend the most money. My expenditure on cables is still max 50% of the cost of the connected components, however the total expenditure on wire puts that at the top of the list.

In order -
- Cables (total for all cables)
- Pre/power amp 
- Speakers
- Front end (cdp)
- Isolation
- Conditioner
- Racks/tweaks

Speakers vs amps breakdown -
- Pre/power amps - 55%
- Speakers - 45%

I feel like i’m sticking to my guns and following my ’balanced system approach’. I believe that is the right approach to achieving the best sound.

Brain. It needs some time to discover which manufacturers have absolutely no idea about High End.
Stillpoints under everything, including an ess rack.

But the speakers would be the most expensive if I purchased them new.
The only surprise I have in the responses is that for a few, cabling has been the single biggest expense. 

In my system, I've probably put less but close to 10% for wire but my results are a bit skewed because I've built some of the power cords I use and I also built one of my IC's
Room by a large margin

TT (Table, arm, cartridge a tie)
Phono preamp (close second)
preamp linestage

This little exercise shows me how overpriced cables are even as crucial as they are to a system.   For me, once I got my source right it made fitting in the pieces downstream easier.

I have an 800.00 power cable on my 2750.00 amp. Well worth the quality in sound. I think about 3000.00 on all cords/cables in my about 15000.00 system.
Sunk the most cash into my 1st wife.
Equipment purchased new: Speakers followed by the CD player.

Equipment purchased used: the amp

Cables and tweaks less than 10% , overall.
OK, I finally decided to chime in:

About 25% each on; speakers, Amp/pre, DAC & USB converter, cables. Everything bought at discount, hence percentage does’nt reflect retail price.
#1 amp 
#2 preamp
#3 source
#4 speakers
#5 cables

In descending order according to MSRP:

Line stage pre-amp, phono cartridge, pick-up arm, SACD player, power amp, turntable, phono amp, loudspeakers, subs.

The pricing is complicated by the fact that some pieces are DIY, some used, and some vintage. So the prices don't really reflect anything in particular. A completely different list would result from the actual prices paid.

WIFE no contest!
For a while it was Super DH Cones, I must have had fifty in the room, under components, under speakers, under furniture, on top of speakers and under stacks of those 4" ceramic tiles that were kind of a passing fad about ten years ago, sometimes crowned with Brilliant Pebbles. The Supers ain’t cheap, either, $150 for a set of three.
+1 sksos1

Second was the kids!
Preamp.... It's the most important component in  my opinion..  My speakers ,amp , and DAC were a little less and were about the same price each.  

Of course speakers are the most important but there are a lot of great ones out there.  Upgrading my preamp made such an improvement that I put off buying new speakers in favor of a new DAC.    I ultimately upgradedecided my speakers but honestly don't think I would have benefitted as much if I didn't upgrade the preamp first .
The most expensive piece I own is my pre-amp.  Most expensive new or used (as I bought it).  My speakers are DIY bought used, but given the cost and relative rarity of the drivers, they would be the most expensive piece to replace if I had to build them from scratch. 

Speakers-Amp- Pre-Turntable/tonearm-Cables-Streaming source/DAC-Power Conditioner-Tweeks-Stand, in descending order.

 With the condition that CDs and LPs come a long way first, but much less painfully as they were acquired over 30 years.