How to add depth for classical music

I'll echo others in saying that if you want to spend your money wisely, ignore any advice from millercarbon.

Image depth is almost always dependent on how far out your speakers are from the front wall (the wall behind them).  The further out, the deeper the soundstage.

I endorse many other comments on room treatment.

The SF Venere's were an entry-level product from SF and frankly not up to the standard of some of SF's costlier designs.  I auditioned the 3.0's years ago.  In a brief in-store audition they were initially impressive, but then I came to realize that that was because of what I called a technicolor sonic presentation, which will tire over time.  Kind of like the way TVs are demo'd in stores, with all the settings maxed out.  But I think a lot of what you are experiencing can be tamed with room treatment.

Remember, too--there are several threads on this subject--that a full-scale symphony orchestra is, by far, the hardest kind of music to reproduce convincingly in a domestic space, so it's never going to be as satisfying, mutatis mutandis, as, say, a well-recorded jazz trio.

That the depth perspective would have been less built out or specific than very highly time-optimized impulse-tweaked speakers—Anthony Gallo's Strada 2 for example—was par for this course. This included a certain looseness in the mid/upper bass registers....

...  That densely layered orchestral or soundtrack strings would sort and separate out less acutely was a logical byproduct of the very same organic voicing.