New Partnership Brings New Design for Sol Republic Sol Republic knows a good partnership when it sees it. After Michael Phelps wore a pair of Sol Republic headphones during the Summer Olympics last year, the company quickly signed an endorsement deal with the swimmer. Its latest collaboration is with Tokidoki, the Japanese-inspired lifestyle brand created by the Italian designer Simone Legno. Sol Republic, known for making headphones with interchangeable components, released two new designs Tuesday that are infused with Tokidoki's distinctive style. The new designs are part of Sol Republic's Tracks line of on-ear headphones that allow users to mix and match headbands and cables to create their own look. The line starts at $100 for Sol Republic's V8 sound engines, a virtually indestructible headband and cable with an in-line microphone. The headbands come in a rainbow of colors and slide into the ear cups, which hold the sound drivers. The cable connects to the bottom of the right and left ear cups, with an in-line microphone and music controls that are set in a yoke at chest level. Each component is also sold separately at Sol Republic's Web site. For an extra $30, you can upgrade to the Tracks HD, which come with V10 sound engines. The sound of the Tracks HD headphones that I tested was clear with a deep bass, and it got even better at higher volumes, especially for electronic and rock music. The Tokidoki headphones, which cost $150, have the V10 sound engines, but also come with a Tokidoki bag. Sol Republic also offers a brightly hued design from Deadmau5 and a U.S.A. theme inspired by Mr. Phelps, both for $150. The Tracks line also includes a pair of $180 headphones called Ultra that are geared toward audiophiles. The interchangeability of the Tracks headphones is a clever idea, especially if you like to wear your headphones as a fashion statement, but it comes with a drawback: the fit. The ear cups don't swivel, and although they were comfortable, I could not get them to sit on my ears properly. The fit wasn't perfect, but at least they looked stylish.