Lack of depth problem

Lets start very simply - perhaps your speakers are too far apart?

The speakers are about 9' apart center-to-center, and 2 3/4' to the side walls (from center of each speaker).

Can you move each speaker 1 foot in and place them 7 feet apart. It will not throw quite as wide soundstage but it will give you more depth.

Alternatively, as Bill suggests - try toeing them in quite heavily.

Vet,

Your JMLabs tend to have a dip in the upper midrange off axis - if you trust these measurements - so this region will be particularly weak from your seated position: well back where you likely get quite a lot of reflected energy of which a lot less will arrive from the upper mid range.

A vocalist (normally placed out front in a mix) may appear more distant becuase of this feature. Conversely percussion may jump out at you because your speaker is quite strong in the 5K to 10K region (where you get the "slap" as stick hits skin). Since drummers are normally placed further back in a mix then this may bring the drummer perceptively forward. Drummer forward and singer backward = might mean perceptively less soundstage depth on most mixes.

Reverb is the other aspect of depth perception - if too much side wall refelctions are interefering with you hearing the reverb off the recording then this might be a factor in reducing depth.

However, I do hear vocal moved to the back and drummer to the front as Shardone pointed out. Good catch!

Then you can do several things.

1. Speakers closer together and away from side walls.
2. Sit much closer to the speakers (or bring the speakers closer to you)
3. Toe them in as you have done (this reduces reflections and increases primary signal)
4) Use a PEQ or tone control to cut or roll off slightly from 5K upwards (this will place percussion further back)
5) Heavy room treatments to absorb more high frequencies.
6) If none of this is suitable then you may need to change the speakers (although JMLabs are exceptional - so this is not an easy task) - but basically it is possible that these speakers do not suit your room/listening/far-field placement. Look for speakers with a very even horizontal dispersion right across the entire frequency range (no dip in the upper midrange) - these will most likely give you more of the depth that is actually intended on the recording. You can see this on the speaker dispersion plots. I suggest a three way with one or two small 3 inch midrange woofers would work best for your far-field listening setup.

FYI: All large 6 inch woofers are simply not suitable for far-field listening as they all roll off around 1 Khz - well before a dome tweeter can take over. Some manufacturers use a phase plug to help improve dispersion. ATC get round this problem by grafting a midrange dome onto a 6" woofer for their two ways. Others will crossover the tweeter very low but this usually results in compression at high output levels needed for farfield. Others go to a horn design on the tweeter to get more output (which tends to narrow dispersion also).

they all roll off around 1 Khz - well before a dome tweeter can take over

What I meant to say is that the horizontal dispersion rolls off. (this is caused by beaming)

Another way round this is to use cones that flex allowing the centre part of the cone to decouple from the outer edge - this is called controlled breakup and you can see it on some woofers with "rings" although you do not have to have rings to exploit cone flexure - it has drawbacks in temrms of added distortion and an uneven frequency response.

I have some Wagner where the chorus sounds like it is in the next street

good tube amps with good output transformers, also have depth.

Good point - the output transformer coupled with speaker impedance variation with frequency will generally have a marked audible impact on the SPL with frequency - this can change the soundstage depth much in the way the mix engineer applies EQ to individual instruments to get a desired depth. Bear in mind that the mix engineer will also play with reverb - stuff that is placed far back will have more reverb added and highs cut - stuff that is forward in the mix will have no reverb (like vocalist or lead guitar) and an upper midrange/treble boost.