What's the weak link in my system?


     I've pieced together the best budget system I could afford over the years but I'm just not thrilled with the sound I'm getting. Can anyone help me identify the weakest link (s) in my system so I can upgrade? I only have the budget to upgrade one piece at this time. I'm most interested in listening to vinyl.
Currently Configured:

Pro-ject Genie 1.3 Turntable w/ Sumiko Pearl Cartridge
Bellari VP 130 Phono Pre w/ Tung-Sol Tube & Replaced Power Supply  
Marantz CD 6006 CD Player
Parasound P3 Stereo Preamp
Parasound A23 Power Amp
PSB T6 Platinum Speakers
Bluesound Node
AKG K702 Headphones
Audioquest Daimondback Interconnects
Audioquest Rocket 33 Speaker Wire

Also Have:
NAD C235BEE Integrated AMP
Monitor Silver RS6 Speakers
Marantz SA8260 SACD Player (Used to sound great but doesn't work consistently - not sure if worth having repaired)
Musical Fidelity V Can Headphone Amp


So.... I think I have put together the best possible system configuration using what I have. What would be the weakest link / first to upgrade? Turntable? Phono Pre? Pre-Amp? Suggestions of products to upgrade to without breaking the bank? I've accumulated a bunch of stuff but I'm really a novice so any and all feedback would be greatly appreciated!   

jdm11
As for speaker placement and room modes, the simplest way to procede is to use REW (room equalization wizard, a free software package, see here: https://www.roomeqwizard.com/) and a cheap calibrated microphone to measure in room response. I am sure you will be horrified. Next, move the speakers around and add some rugs etc, as per advice here, to see if you can improve the response. If you want to improve the response more, you will need to use a parametric equalizer, either in software or in hardware. See here for a software one: https://sourceforge.net/projects/equalizerapo/

Great advice on the digital equalization. Then you can just throw your turntable and LP collection away. lol

Dave
Sure, if you want good audio you have to say goodbuy to the vinyl romance anyway.  However, if you really want to hang on to your vinyl setup, you can also do the equalization in hardware.
Moving speakers around trying to find the best locations is like trying to solve 3 simultaneous equations in 4 unknowns. You'll never be able to find the absolute best locations without the out of phase track on the XLO Test CD. The best you can do is find local maximums. This is one of the few cases I can think of where measurements are superior to listening.