I personally was not impressed with the OEM case for the Sonos Ace. I’d like to share with you the case I prefer that was designed for Apple’s AirPods Max (of which I own a set); but works quite well with the Ace headset. Speaking of Apple’s AirPods Max OEM case...that IMO was a joke and ½ .

Getting back on point...the case I prefer is a bit on the pricy side at $99 made by WaterField Designs in San Francisco, CA. Materials are Leather and Ballistic Nylon with moisture proof zippers. As you will see my choice is black leather; but for the more adventureous there is a white leather option. It’s not as compact as the Sonos Ace OEM case which may be a problem for some. However, IMO its AIO nautilus chambered design is a more complete package for protection, travel and/or EDC. 

Below are pictures that show a comparison to the Sonos OEM case for the Ace and features of the case I prefer.  Enjoy!

Side by Side Comparison

Height Comparison 

Volume Comparison

Interior Fit and Battery Compartment. Observe the rectangle outline just below the bridge of the Ace headband which shows the battery. Battery measures (inches) 2.5(L) x 1.5(H) x 1(W)

Protective padding in Top of Case

Zippered Accessory Pocket for Ace Cables

Rear Mesh Pocket for a Phamplet 

Easliy Charge Ace Headphones in Case

Edit:

For most users the case will accommodate the headphones personal fit adjustment you selected without having to collapse the sizing to fit into the case as one must do with the Sonos OEM case.