Solid state amplifiers and sound stage, especially front to back "depth"


I've been enjoying my trial period with the Van Alstine SET 400 stereo amplifier. When I'm done and have collected my thoughts, I may write up a summary.

In the meantime, a question for folks with more experience. I've noticed is that the amp produces a sound stage that is nicely defined and articulate from left to right, but not as much from front to back. (My Adcom was also unable to create sound stage depth.) I know my room is capable of that sound stage because my tube amp accomplishes it.

Question: Is it typical of solid state amps to have less of a front to back sound stage than tube amps? Do they vary in this regard? Or, perhaps, am I failing to do something -- such as re-position my speakers? (After all, I immediately get that sound stage back when I switch amplifier without moving anything else.)

If you have any experience with solid state amplifiers and sound stage -- front to back, left to right, or whatever, I'm curious.

This is not about me keeping or not keeping the amp. There are many things I already really like about it. But I'm wondering about this aspect.

Thanks.
128x128hilde45
Thanks to recent posters. 
@avanti1960  Speaker positioning cannot be the factor responsible, as previously explained. Thanks for other insights, though.
I think it's safe to say that Ralph is a Renaissance Man.

@niodari
The company is Atma-sphere Music Systems. No affiliation.
Thanks @lowrider.. for letting me know the credits of @atmasphere . I had a quick look at the site, it made a solid and convincing impression on me. I wish him all the best in his art of design perfect tube amplification.
@niodari FWIW we've been working on a class D amp of our own design for the last 4 years. It **should** not matter to reproduce depth if the amp is tube or solid state. But the simple fact is most solid state designs have troubles in this regard- but not all. 
The most recent podcast from Darren and Duncan sheds some light on the issue of left right and depth soundstage, particularly the kinds of factors involved in the design responsible for enhancing or limiting them. Also some interesting comments about class D amps and soundstage. Look for the episode with the title mentioning sonic holography.