Zac Posen has just moved studios, up from his longtime space in Tribeca hard by the entrance to the Holland Tunnel to the tonier and more corporate environs of Fifth Avenue and 54th Street. Brooks Brothers, where Posen signed on as creative director last summer, is not far away, and he lives in Midtown now. The designer’s center of gravity has shifted, and there was a noticeable change in his Pre-Fall collection. Call it a new softness. His clothes are as body-aware as ever, but he’s chosen materials with a relaxed ease. Jersey knit clings without all of the seams required to get the same effect out of the evening fabrics he’s tended to prefer all these years. A long dress in a navy and black micro floral with a scooped “Martha Graham” neckline was particularly striking, but he also used the stuff for a charming, knee-length day dress that will find a lot of takers. Perforated silk in jewel tones, another new material chez Posen, was a little less compelling. As usual, evening was where Posen really shined. A bonded satin crepe cape-back gown with cutouts at the shoulders in the mauve-ish shade that Pantone has just named the 2015 Color of the Year (a total coincidence, the designer insisted) is begging for one statuesque celeb or another. Posen was in the news after posting a pic of Rihanna’s visit to his new space on Instagram, but he wasn’t telling which looks she has her eye on. The winner in our book was a covered-up printed chiffon gown with buttons down the bodice and a frill of ruffles at the hip.