The group also recently signed up car security vendor Auto Page and car stereo specialist Custom Sounds.
Rockford national sales director Rob Wempe said the company joined ICE because many of its retail members are leading car stereo specialists.
Other ICE vendors include Pioneer, JL Audio, Boston Acoustics, Aamp of America and Metra.
ICE, launched in 2006, has been the sole car stereo buying group, however, the Mobile Enhancement Retailers Assn. (MERA) recently announced it will join with the Brand Source/AVB buying group to create a new car stereo buying co-op called Mobile Entertainment Source (MES), which will make its formal debut at International CES next week.