The program ends with the work its creator said “is the best thing I ever composed or shall,” Pyotr Ilyich Tchaikovsky’s powerful Symphony Number 6 (Pathetique), a profound masterpiece that demands the best of any orchestra.

At rehearsals, all are on a first-name basis, even with their young and knowing artistic director and conductor, Alejandro Gomez Guillen. They’re not in formal wear, but shorts, jeans, T-shirts, sweatshirts, sneakers, sandals. Tension is absent. Comfort abounds.

I attended a BSO rehearsal last Tuesday evening, a portion of the weekly two-and-a-half hour session that — because it is close to concert time — has been beefed up with additional rehearsal periods for preparation. Much of the evening was devoted to sectionals, — strings, brasses, and so forth — focusing on refinements. Maestro Gomez Guillen was fully in charge. He sat up front, facing a table covered with scores. He gave the downbeats. He waved the hands. He stopped the music, often, to address a point, through spoken explanation or sung demonstration; he has a fine and trained voice that can belt or croon and cover a string of octaves. What he told or sang to the players, they seemed to understand; on replay of the faulty passage, one could hear immediate change.

In addition to the affable Donna Lafferty, executive director of the orchestra and a trombonist within its ranks who teased me into coming to the rehearsal, I spoke with four BSO members. They each met me with the joy of belonging:

• Frank Watson, double bass, who playfully asked me to guess his age: I said 70. His fingers pointed upward. I said 75. His fingers pointed upward. I said 80. His fingers pointed upward. He’s in his early 80s, joined the orchestra about 15 years ago, plays with other groups serving different repertoire, and looks forward, he said, to every rehearsal and every concert of the BSO. “I don’t want to miss a single one. This is where I like to be,” he insisted.

• Todd Davidson, principal trumpet who studied in IU’s Jacobs School: he has taught music, worked at The Herald-Times, and now in software technology. He, too, joined the orchestra 15 years ago. He spoke approvingly of Maestro Gomez Guillen, describing his work as “sensitive, detailed” and very helpful because of his “great sense of phrasing, his ability to shape musical lines.” Davidson continues to “spend an hour or two every day practicing. Music has always been part of my life.”

• Victoria Hilkevitch, first violinist and retired professor of psychology: She’s been with the BSO for 20 years and told me being with the orchestra “has been like being with family.” She praised her conductor. “Alejandro is the first artistic director we’ve had since I joined who is a string player. So, he really knows our problems and has a way of telling us how to fix them. He’s engaging. He’s challenging. He listens to us. He’s humorous and can laugh at himself. Alejandro has worked hard to make us play more like a chamber orchestra, with a sense of closer unity. I love that.”

• Simona Staneva, principal second violin, who just joined the orchestra a few months ago: Simona came from her native Bulgaria in 2015 to study at the Jacobs School, where she is a junior. Her purpose in joining the BSO: to get more experience. Analyzing her conductor’s contribution to that experience, she said she has benefited from “his patience, ability to explain clearly, and sense of balance.” She has found him “to be a good person to be around, emotional in a good way, and willing to show us on the instrument how something should be played.” As for the BSO, “It puts me among musicians of all kinds and backgrounds and ages. I value that.”

Join the enthusiastic four Bloomington Symphony Orchestra players mentioned above, their colleagues, and their conductor next Sunday.