How do I get the best soundstage?

I would rely upon your digital setup with music or a test CD for speaker placement. I like a laser pointed at a target at the listening position to achieve symmetric toe-in. The distance between the speakers - obviously including symmetry to the listening position axis - is also a big deal, ime. I do not know if your speakers are sensitive to rake, but some are. That said everything in the audio chain can change the perception of soundstage.

Soundstage optimization is not easy.  It can be hard identifying the weakest link in the chain that is compromising spacial clues.  For most situations, the most likely culprit is the speaker/room interaction.  You want to really kill early reflections, that is, those with a delay of less than about 12 millisectonds.  If you don't set up and treat your room/speaker/listening position in such a way as to reduce those early reflections to about -20 dB relative to the direct from speaker sound, no other change in equipment is going to fix the problem.  Download Room Equalization Wizard (free software) and learn how to use it.  The impulse graph will be your main tool on optimizing spacial clues.  

REW is a powerful tool that no audiophile should be without.  I once was blind, but now I see.  REW is that good.

Almost makes me miss MC.

Imagine if clubs and concert halls and all the other assorted auditoria in which music is performed were subject to the electronic constraints that Mijostyn prefers to apply in his home system.  Would it add to enjoyment of the music?  Would we even like it?  I am not posing this question to criticize Mijo; it's just food for thought.

@hysteve , getting a system (room included) to image correctly is very difficult given the equipment most people have. Most of the electronics, cartridges and even speakers are capable of doing this at a reasonable even surprising level but the system needs to be calibrated to the room it is in and any other errors corrected. 

For a proper stereo image symmetry is the most important factor. The performance of both channels (room included) needs to be identical in phase and frequency response. Early reflections have to be absorbed or speakers need to be directional to prevent them entirely. It is not important that the frequency response overall be flat but if the treble is up 3 dB in one speaker it has to be 3 dB up in he other. The channels need to be matched as closely as possible to prevent smearing the image to one side or the other certainly within 1 dB 100Hz to 12 kHz.  Digital signal processing is the only way to achieve this. You can get within 5 dB with room treatment if you know what you are doing. To know what you are doing you need a measurement microphone. Digital room correction preamplifiers will do it for you. The Anthem STR is in your price range. DEQX is releasing new units in about three months. They look great but the prices are not yet available. Trinnov currently makes the best unit but it is $11,000. 

Some people will never experience a system with SOTA imaging because they are digital phobic. But, you seem to be fine with it. The only thing I would change in your system other than getting a Digital Room Control preamp is, get rid of the unipivot tonearm on the VPI. It is a terrible arm. Get an arm with proper bearings. VPI makes one now that is an easy exchange. 

I haven't listened to your speakers but they may not be the best for soundstage.  If I was in your shoes, I'd consider that.  Try to borrow some more conventional 3 way speakers with an exceptional midrange.  Midrange is where the soundstage exists.  Not sure how horns affect soundstage.  Some others with horn speakers may chime in but I would wonder if the horn design is affecting soundstage.  

Agree with speaker placement.

Also, for soundstage, I think your best results come with the minimalist approach.   The less times the signal is touched by the system the better your soundstage will be.  Pass is a good amp but ss amps always do a lot more to the signal.

Jerry

Don't forget about treating the room. The best sounding gear in a crappy sounding room will sound crappy.

This worked best for me for speaker placement. Get those speakers away from the wall.

Posted twice:

Oh and yes yeti42, I am really enjoying the Voltis now. They are the entry level Razz. I had to really work to get the bass output ie with upgraded DAC, reclocker and cables. Each incremental upgrade helped and the less loss cables really did finished the job. I don’t look for bass when it’s not in the music or boomy bass when it is. It seems perfect now. 

Thanks to everyone for taking the time to write some really helpful info! 

Cheers

Gotta agree with speaker placement too, plus a well recorded/engineered LP. IMO, if the soundstage is within the recording(s), you should be able to reproduce it, and it seems you have the equipment to do so.

That said, yes, I think both the cart and phono pre can get the most from any recording, including the stage, but you can’t reproduce what isn’t there.

As @yeti42 said, try the Sumiko Setup.  These are the instructions I use: https://www.audioaficionado.org/showthread.php?p=979168

You're not going to get it on the 1st, 2nd or 3rd try but don't get discouraged.  I have the patience of Mike Tyson losing a boxing match and I was able to stick it out and get it mostly right.  You'll try it and not really hear much difference the first few times. Then you'll have an "ah ha" moment. After listening for awhile longer you'll realize it was just an "ah" moment but now you know something is different. A few more tries and you'll get it. Best bass doesn't mean loudest, it means sound pressure; you can feel the difference.  At the end the speakers may not be the same distance from the front wall or even the exact same toe in. Some people can't stand this and just give up. That's ok. It's not for everyone. At least you'll get a taste of what you should be looking for regardless of your setup method. My local dealer uses this on all his demos. He doesn't even put marks on the floor. He sets the speakers new up every time. Once you get good, it takes about 15 minutes to get most of the way there.

I second that you should spend as much on a phono stage as the TT + cartridge… the Phonostage is critical in imaging. I would recommend looking at Audio Reseach  PH8… or the best used you can get in that series. I had a similar table and the sound (and transparency) increased dramatically with each PH upgrade. Presto also  get great reviews… but I think ARC wins for durability.

Speakers and placement are critical. If you haven’t point them to cross about 18” behind your listeners seat. Then slowly decrease the toe in. The soundstage should slowly expand. You want to go out until just before the central image starts to weaken.

Speaker placement.

Sell the Volti’s and get Ohm Walsh’s. 3-D room-filling sound from any listening position! I have a pair. An astonishing speaker! Nothing else will make as big a difference!

Speaker setup plays a big part. Do a search for Sumiko Masterset and give it a go, all it will cost is time.

Cartridge wise a Transfiguration isn’t a bad place to be but when setting up a unipivot arm measure VTF at record surface height, or if you can’t accept that it will measure higher than it plays and use your ears, just using the measurements for reference.

Something better than a project phonobox might be a good move, if the Pass has a built in MM stage consider a SUT but if it doesn’t there are some fine stages out there.

Volti keep saying their speakers are fun, are you having any?

The phono preamp is as important as the turntable itself. The cartridge is the last in the vinyl chains as far as importance. Of course you need a good cartridge. But Origin live says to spend 30% of budget on each, TT, Arm & Phono preamp and 10% on the cartridge. I believe this to be pretty much correct.

The speaker sure do make a difference also. They should be equidistant from the side walls and not too close to the back wall. Mine are about 3 1/2 ft. from the back wall to front baffle.