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.

Eddie