From Allmusic: The first equale has a stately sobriety and hymn-like character, but in the end registers with a funereal quality in its solemnity and quasi-religious sound. The second piece is slower and more ponderous; its glacial pacing and barren sound world relate it more to gray moods than to lugubrious ones. The third entry here is closer in spirit to the second, but the music is less sonorously fluid; it stops, restarts, and stops again, especially in the latter half.
These 3 pieces are very short, as short as the Missa Solemnis is long! Still, they are interesting as yet another facet of Beethoven's art.
Jaén Low Brass; The Three Equals --- Beethoven
On the theme of brass, here's an interesting arrangement of the Egmont Overture for full "Trombone Ensemble"!
György Gyivicsan's trombone class plays Egmont Overture from Beethoven (Arr: Áron Simon). Trombone: György Gyivicsan, Dávid Lévay, János Angyal, András Pálfy, Péter Vörös, Áron Simon, Zoltán Takács, Ádám Moldován, Timpani: István Szegény. Live recording - Nov. 29, 2010.
Beethoven: Egmont Overture - Szeged Trombone Ensemble
The 5th Symphony gets the all-brass treatment here, by the Brass ensemble of the Mariinsky Theater, Conductor Alexei Repnikov.
Symphony No. 5 (Ludwig van Beethoven) 1 Allegro con brio
Of course if one wants to go extreme, there's this "Piazolla Tango Nuevo" arrangement of Fur Elise:
Tango For Elise - Blechschaden - Brass Ensemble - Beethoven