What's the weak link in my Analog chain?

I have:
Souther Linear Tracker Arm
Clearaudio Maestro Satine wood
Manley Chinook (on loan from dealer)
It all sounds very good, but still can't match my Theta GenVIII Dac Pre using a Sony777ES SACD player as a transport. The sense of space, of being in a real concert hall on clssical recordings is noticably better on the digital rig. I'm wondering what to change in the analog rig to meet of exceed the quality of the digital rig.
Quick and easy, upgrade your VPI to Mk IV, with the super platter. More expensive., trade your VPI and Souther for a VPI Classic, Oracle Delphi, Sota Star or Basis 2200 with their appropriate arms, JMW, SME or Vector. then make sure every part of your front end is properly aligned, including VTA, Azmith, VTF and place your VPI on a seismic sink or some other isolating support. Your vinyl front end should easily exceed your digital front end.
Sounds like more of a set-up issue as that system should be able to outperform your digital set up; IMO.

The Souther is an extremely resonant tonearm. It is light on body and has artificial highs (ringing). Those who loved it would proclaim: "air.....transparency.....air........transparency......", and that's the ringing. It does not represent what is on the record. I'd upgrade that first.
Isolation. Not you- the turntable. Remember, the stylus is picking up vibrations that are being amplified 10,000 times! Okay, 66dB or more. It is a big number, I just don't feel like doing the math at the moment. So the smallest vibrations, even from the air can affect playback performance. The VPI table has no suspension, therefore, isolation outside of the tt chassis is extremely critical. Hey, I just learned for myself not long ago how much isolation can impact even my suspended turntable. Isolation is first and then speed control is next. Being dialed in to 33 1/3 is important, but make sure the variation per rotation is small. I don't know if you can adjust belt tension on your rig, but that can affect the sound. You don't want too much or too little. Finally, look at wiring; but this is not where you should start. I think isolation is paramount. With improved isolation expect the bass to get tighter and clearer and the soundstage to open up well beyond your digital rig. Based on other comments, try some dampening material on your tonearm. You might even start with some rubber bands wrapped tightly in different locations on the tonearm. Be sure to rebalance. Also, do not add too much weight or it might create new issues. You have some very fine equipment and possibly some simple steps will result in very satisfactory results.
For no cost you could start with confirming cartridge loading and gain and alignment. I agree that proper isolation is always good. Beyond that, I'm not really familiar with your components.
Thnaks for the responses, all. I think part of the problem might be break-in. The Chinook was brand-new in a sealed ox when I brought it home (Ihave teh option of buying it or returning it ot the dealer who will use it as a store demo). I have about 70 hours on it now, and things have gotten progressively better over time. Also, I went from 200 to 250 pF on the capacitance, which seemd to have cut down on some glare without sucking too much out of the high frequencies. 300pF seemed to darken the sound too much. I played with VTA a bit, by ear, I think I'm in a good spot, not sure if I'm much different than where I started.
Omsted, I wonder about the tonearm, too. Looking at it, it's a wonder that it works at all, much less well. The actual arm is just a 3 inch long piece of stiff wire; everythign else is a fancy, jiggly pivot. In terms of lacking body, though, that's the one area I think I'm surpassing my digital right now. Whether it's a case of all the different colorations cancelling each other out, or what I don't know.
The worst component in that System is the Arm.
I would have to agree with several others. The Souther is a poor design, even more poorly executed. I'd be willing to bet that, ironically, it's causing the classic symptoms of old time digital - constriction, harshness, and several other forms of auditory irritation. If this were mine, I would ditch the arm immediately.