FORT WORTH — One thing you can say about the Hall Ensemble: It has some of the most interesting venues of any musical group in Fort Worth. Friday night’s program (to be repeated Saturday night) was at the beautiful old Thistle Hill Mansion near downtown. It was only the latest in a series of appealing sites in the ensemble’s brief history.The idea of the ensemble, in case you haven’t heard, is to present chamber music as it might have been heard 150 years or so ago — that is, by small groups of musicians performing before small groups of listeners in the rooms of elegant houses.In brief remarks Friday night, artistic director Karen Hall mentioned 19th-century European salons as an inspiration. The program reflected that. The pieces were short, or single movements of longer works, they were highly varied, and they expanded musical boundaries by arrangements that brought bigger works into a smaller space.Bassoonist Kevin Hall deserves special recognition for his highly effective arrangements. He tailored several works for the special needs of the six-member Hall Ensemble. In only one of the evening’s compositions did one really miss the orchestra for which it was originally written. That was Mahler’s Um Mitternacht, and it was the only arrangement not by Hall.The six instrumentalists were the two Halls (Karen plays the cello), violinists Jennifer Chang and Molly Baer, violist Aleksandra Holowka, and pianist Stephen Carey. They are mostly Fort Worth Symphony Orchestra players. This program also featured artists from the Fort Worth Opera: soprano Kerriann Otano, mezzo Clara Nieman, tenor Ian McEuen and baritone Matt Moeller. The first work of the evening was an excellent example of effective arrangement. This was the first movement of Mozart’s great Sinfonia Concertante for Violin and Viola. Chang and Holowka were the soloists and everybody else backed them up — that is, piano, violin, cello and bassoon. On paper the combination may sound a little bizarre, but it worked beautifully and one longed for the whole thing.The rest of the program included songs by Rachmaninoff and Peter Warlock; Fritz Kreisler’s old crowd-pleaser Liebesfreud; the finale of Brahms’ Piano Quartet in G minor; Schubert’s Erlkonig; the famous nocturne movement of Borodin’s String Quartet No. 2; Liszt’s La Danza; and music from upcoming Fort Worth Opera works: Lakme, The Pearl Fishers and Cosi fan Tutte.Quite a mixture, and quite a pleasing presentation. Moeller’s Erlkonig and Moeller’s and McEuen’s Pearl Fishers duet were two of several highlights.The program was sold out, as is Saturday night’s repetition.