How would you prioirtize?

I have been following this forum for about a year now and it has definitely helped me improve the sound of my system without much expense.  I now find myself ready to step up and spend some money for the next few steps in my adventure.  I have come up with 4 areas that could help me rise to the next level.  I would like advice on which order you would take these steps.  I have ability to spend $2-$4k every 6-8 months.  
I currently love my system, but I can hear room for improvement.  With the right record, I can turn it up to around 100db and it blows me way.  Other records don't sound so great even at lower volumes.  I know that recordings differ, but the bass gets boomy and the details are lost far too often.  I can't help but feel that with improvements in my system all records would sound much better.  I want to widen that sweet-spot.  BTW I do clean my records, it's not pops, it's the richness, details and bass definition that is off on some recordings over others.

My system so far:
  • Turntable: Thorens TD:150 / original Kugel arm / DL 160 re-tipped by Sound Smith / on springs-maple board-springs.
  • Power: McIntosh MA 8900 / original power cable / orange fuse (it does make a difference)
  • Cable: Blue Jean 12
  • Speakers: Belle Klipsch / ALK Extreme Slope crossovers / Dynamat dampened / on Hardwood sprung floors away from side and back walls / toed-in.  My system has been build around these 70's era speakers.  I am emotionally attached to them, they have a great story.
  • Room:  25' x17' open space and lively / slanted ceilings / 3 windows on one long side / carpets and curtains.  Listening couch is 9' way from speakers, somewhat mid-room.
Below are the items on my list of improvements in no particular order:

  1. Source: a. Replace the arm on the current TT (AMG 9W2 is an easy swap I am told).  b. Replace the whole rig.  I have always wanted to have a Thorens TD-125 and I am in contact with Dave from Vinyl Nirvana.  Besides being the same vintage to my speakers it has a more easily swappable arm-board.  Arms on my list include Audiomod, Origin Live, Groovemaster, SME, Thomas Schick and a few others.  IMPORTANT:  I got ahead of myself and purchased a Sound Smith Zephyr MMIC that I would like to use on the next arm.  It was too good to pass up...
  2. Phono Pre:  I am most interested in Decware and Herron.  Decware would need a Step-up transformer for the Zephyr MMIC
  3. Isolation:  Solidsteel wall shelf for the TT.  Townsend speaker bars for the 18" x 29" base (I don't think they make podiums that big).  I was originally going to put them on Pavers, but I feel that I should go big after hearing reviews on the Townsend ability to isolate. (buy once buy well)
  4. Cables and other items:  Power cords, better speaker cable, other isolation, room treatment.
Thank you for your time and helping me wade through his information.

I would start with the source.  Upgrade what you want on the front end.  Then isolation if needed for the TT. Then look towards the phono pre.  (I own the Herron, probably can't go wrong there.)

Then equal parts of everything else, as needed.
Slow and steady, my kind of man. What you are talking about is pretty much what I have been doing off and on since like forever. But especially the last ten years or so. One or two great components a year and after a while.... 

You are already off to a great start. There really is no one next step or even set of next steps that are all that much better than any other. At least not that we can help you with. If there is something in your system you feel is relatively weaker, you are less happy with it or whatever, that would be the first to go. Other than that though, it is not like what some people think where you have to do speakers to hear anything else, or your amp is the weak link you won't hear anything until you fix that, this is all bunk. You already know it is bunk because you heard the fuse. Obviously your system and ears are good enough to appreciate that, they are good enough to appreciate everything else. 

Decware vs Herron is a tough call. I have Herron and love it, definitely a keeper. But it does use an op amp while the ZP3 is pure tubey magic. Hard to go wrong. I find that as more time goes by I am even more drawn to tubes and would lean Decware for that reason alone.  

I would for the same reason be looking to upgrade the Mac to Raven. But again if you are happy with your Mac then maybe save that for later. Besides, if you were to do the amp now you would probably go for a Blackhawk or Osprey. But if you were to wait for later after upgrading everything else you might well wind up like me setting your sights on a total end-game Raven Reflection.   

I would highly recommend Origin Live. Their arms just work, none of this BS worrying about compliance, cartridge matching, you can forget all that they just work and produce wonderful hard to believe an arm can make so much difference music.

But without knowing what you have that you feel is weak then the one step I can recommend that will be big value and work no matter what is what you already said, Townshend Podiums. And Pods. They also make a Platform, which is basically the damped shelf material similar to Podiums but with Pods underneath. They can make these to any size, just ask John Hannant he will hook you up. 

With those you probably want to start with the speakers, then turntable, then amp and other components. I am not big on wall racks for turntables but every situation is different. Whatever rack you use the Townshend will still work and be incredible. The stuff I was already using was very good, and some of it even cost more than Townshend, but Podiums and Pods are so much better it is hard to believe. 

Some of this stuff like Townshend you can get right away. Some like Decware you are looking at a couple months build time. Herron I think is about a month.  

Another thing I would do, in between the big components, add Synergistic HFT, ECT, PHT. The HFT will be a great improvement to the acoustics of your living space without making it look like a sound room the way acoustic panels do. You might not be able to do the full room treatment because of the layout but the speaker kits are impressive and work on all kinds of different speakers. PHT on a cartridge are almost like a whole cartridge upgrade. Townshend are of course like a whole new turntable!  

There is some other even better stuff, PM if you are interested in that I will hook you up. 

Couple years from now your system will be so much better it will be hard to comprehend. Exciting times!
I would look at room treatments first, given your open and lively room with an interesting shape and windows. If the addition of significant treatments is a problem, even some minor treatments would probably help.

After that, for better detail retrieval I'd probably upgrade the turntable and cartridge.

Also, hopefully you are normally listening to music around 75dB and not 100dB, to avoid permanent hearing damage.
Slow and steady, my kind of man.
I think that is a bit more than anyone cares to know....
Thank you all, I appreciate the input.
@nekoaudio yes, I only do loud on occasion just to see how far I can go without noticeable distortion.  Mostly much much lower. Do you have treatments that you like? GIK etc or other. It's a tough room due to odd angles etc.

@erik_squires  Same question to you.  Not expecting either of you to solve my room acoustics just a way to begin and tips.  

@vinylzone  I guess I feel my weakest link is the tonearm so your source idea rings true.   For this sweet sounding entry level turntable this creates the problem of options.  Currently good sound, few options for upgrade. 

@millercarbon I appreciate all of your considerate thoughts.  I will definitely PM you as I have more questions.  I have already learned much from your advice to others.  
What is the floor construction? Foundation level or upper level/suspended plywood? If you jump up and down do things vibrate/shake rattle or move? If so isolating speakers from the floor with isolation pads like Auralex Subdude or similar might be first thing to get a handle on to control the bass and avoid obscuring midrange accordingly.

In general you want to understand what makes your room tick before attempting any major changes.

If you clap your hands do you hear an echo?  High ceilings and large rooms can be particularly challenging to tame if needed. 
In the corners behind the speakers, go floor to ceiling with GIK Soffit Traps. ($1K)
Add curtains and a rug if you can/appropriate.

Between the speakers, GIK Impression diffusors/bass traps.

244 Panels at the first reflection points

Note GIK is running about 8 weeks from order to delivery right now.

You can save some money by using ATS panels instead of GIK, but you should still consider their soffit traps as your first purchase.

Expect this to change your tonal balance somewhat.  :)
@edgyhassle for improving the bass, I'd recommend thick corner/bass traps. The brand doesn't really matter, as long as it is thick and actual absorption (with data to back it up, like GIK ). There are a lot of products out there that are advertised as acoustic treatment or acoustic panels that won't really do anything for bass.

It's also very possible your room is hurting the clarity and detail that your setup could produce. Echoey rooms are notorious for making it harder to understand voices, and of course that applies to other sounds as well. In addition to acoustic treatments, just regular furniture and filling the room with stuff can really help with that. Adding heavy drapes over the windows is better than nothing.
@mapman Yes sprung floor, plywood hardwood planks between suspended beams.  Prior to adding the springs you needed to be careful on how you approached the TT for it not to bounce. I would tiptoe.  Now it is good unless I jump.  No echo clap, learned this one from my friends at Meyer Sound in Berkeley.  Furnishings, carpet , curtains and shelves of records seem to help control the sound.  The walls do need help.  I definitely need to isolate the speakers, thanks.
@erik_squires  Thanks Erik, thankfully I can adjust attenuation for tweeter and squawker with the ALK crossover, makes it easy for any room treatment changes and absorption.  I have played around and gotten creative with treatment using cloth screens to see if it makes a does.  More fun ahead.
My bad- too late to edit, don't want to remove a whole post, but I screwed up, the Herron does NOT use an op-amp! The MC stage uses FETs that are arranged in a unique triode mode.
that didn’t take long.....

have you figured out what the NAND gates do ?????

You got a lot of good suggestions. A quick and easy and inexpensive thing that will help improve sound quality is to get rid of those blue jeans speaker cables.  I am not a proponent of expensive cables, and BJC makes some decent cables, but when I tried their speaker cables they seemed to suck some of the life from the music. 
Do Try various Sub Plinths and Footers arrangements under the TT.
Energy is transferred to a TT through Air and Structures.

The Sub Plinths and Footers will attenuate the environmental effects.

I have not at any time found this practice to be a wasted investigation.
The outcome has been to discover a comprehensible perception of a  improvement to the presentation.

My Investigations, 'that are limited' for working with a Cabinet Speaker Set Up, are that Sub Plinths Produce noticeable improvements.
The Perception of a sharpening of the Imaging and producing a Leaner Bass Note with a improved Mid - High Projection can be attained,
this is at the cost of a Broad Soundstage.

Seating Suspension Footers between the Sub Plinth and Speaker
( I use Two Tiers of Sub Plinth each with Spiked Footers, with a Set of Three  AT-616 seated on the Top Tier ) has in my experience added a improvement.
The addition of Suspension Footers Widens the imaging and separation, 
broadens the Soundstage in all dimensions, and there is a perception tht the performance has a increased presence, but not as a added weight or richness.  
Note: I feel sure that there will be a group of listeners who would be very satisfied with the Speakers Performance, when seated on the Two Tier 
Sub Plinth before the Suspension Footers were added.

Creating a Two Tier Plinth is Relatively Cheap and worth the time taken to investigate the effect it can have on attenuation within a environment.  
Before an amateur will buy random acoustic panels he must order acoustic analysis of his room. Some rooms are simply awful for sound, some are good. Mos of the cheap acoustic panels are useless.

Instead of GIK you can order room analysis from Vicoustic (I paid 50 EUR for complete 3D model of my room with acoustic treatment).

If you want to learn more (how difficult it can be) you have to watch his lectures online (very informative).

Then you will realize how much you have to pay for a proper acoustic treatment if you will ignore all cheap foam panels flooded the market (or some junk from the manufacturers who promises you a great result if you place a few square little something behind your speakers etc).

Real acoustic panels are made of natural wood, they are big and heavy, this is what professionals have in the studios (like this diffuser).

Absorbers are easier to make, last year I discovered Basotect (remember BASF ? ), they can make any custom size and color, look on their site for pictures.

P.S. I bought these absorbers from Vicoustic two years ago, sadly this model is discontinued. Took this image two days ago thinking how I’m gonna glue them. Those type can be nice in any interior design, I have only two colors. The Wavewood are on my wall behind the speakers for a long time, they are nice. For the ceiling I got Multifuser DC2.

Actually you need panels everywhere (all walls and ceiling), so it can be ugly and expensive!

Here is my old thread about it (hope it will help a bit, maybe).

this is at the cost of a Broad Soundstage.

The cost is too high. Especially considering you can have it all.

@chakster , you want to use ceramic tile adhesive for those, use a base trowel to apply the glue and stay 1/2" away from the edges. You will be able to adjust them a little once they are on the wall and the adhesive has enough body so they will not move or fall off whole they are drying. Otherwise excellent advice. You have to know what you are dealing with before you deal with it!
Vicoustic supply their own glue for the panels.
Some of them can be glued with liquid nails, some of them are not.

I’m searching for the right glue which is safe for acoustic foam (on the back of the panels). Those panels may look like concrete, but it’s just light weigh acoustic foam in fabric. Still can’t decide on the pattern, so many combinations, here is the latest one.