There are probably as many, or more, ways to deepen into the soul level as to Big Mind.
For me, the heart prayer, Christ meditation and Breema are the ways I work with the soul level.
The heart prayer and Christ meditation is a second person practice, awakening Spirit - in its Christ aspect - as Thou, and also awakening soul as first person, as I or me.
Breema is a first person practice, awakening soul as I, me or mine.
With the Christ centered practices, there is a sense of deep fullness and richness, of unspeakable beauty, bliss, pain, longing, joy, and sometimes of losing any sense of separate self in an immensity and infinity of bliss and radiance.
In Breema, there is a similar sense of fullness, depth and richness, yet with an absence of the longing, pain, and intensity of the prayer. There is just a sense of calm fullness, of being home, of no separation, a quiet bliss and joy, and of being participation - of all of me participating.
So the fullness and quiet bliss of soul is there in both cases, yet with the Christ practices more intense and transcendent (although also very much in and through the body), and with Breema more quiet and body centered.