Soundbox is dedicated to new music, Salon 21 to piano performances in intimate, nontraditional settings. So how about a piano performance of new music from Poland and the U.S. in an intimate, nontraditional setting? Sounds like the cue for a collaboration, doesn’t it? The result, “Parallels,” includes works for string quintet by Żaneta Rydzewska, Aleksandra Chmielewska, Julia Seeholzer, Laura Harrison and Rachel C. Walker. Jill Jantzen, Salon 21 artistic director, joins the Cincinnati-based 4-Way Quartet (one supposes they head to the chili parlor after rehearsals) at the Aronoff Center’s Weston Art Gallery.