What is the ideal volume setting?

Amen to that!

Example: 1. Turn on your SPL meter. 2. Play the Calibration Track. 3. Adjust your volume until it reaches the specified SPL. 4. Enjoy the music the way the artist intended.

I'm not sure I understand what the problem is.  As has been pointed out well recorded Classical music can have a very wide dynamic range; a good thing.  Live, the range is even wider.  Is the problem for you that you have to set the volume such that for the soft spots in the music to satisfy the volume is then excessive during the loud passages?  A common reason for this kind of dissatisfaction is that some speakers do not have good resolving capability in the area of micro-dynamics when played softly and "like" to be played louder than other speakers which do better in this area; or, need better amplifier matching.  When this problem is addressed properly low volume passages in the music will still have the proper musical impact so that the overall volume does not have to start so high that it becomes overbearing during the louder passages.  In my experience with my systems over the years Magneplanars have been particularly difficult in this particular area and Quads particularly good.  What are your speakers and amp?  

I find there is an ideal volume level where everything sounds as it does in a concert hall.  Every classical recording is different in that regard.
it isn’t so much that I can’t hear detail at a lower setting. I can.
There’s just an optimum level where everything sounds “right.”
I have modified Dalquist DQ 20 speakers, NuForce monoblock amplifiers, along with a CJ preamp.

Thanks for the explanation; I understand.  I suppose it would be nice if levels were standardized on discs, but.....Do you always sit at the same distance from orchestras when in concert halls?  Be careful what you wish for.  Classical recordings are deliberately recorded with different perspectives; some to give a close to the orchestra perspective and some further back.  For concert hall realism, it seems to me one would have to adjust the volume for each recording anyway since the recording with a close-to-orchestra perspective would have to be listened to louder than one recorded further back for it to sound "correct".