In the past, the Sirius XM Pops channel, which aired classical music, was broadcast in 5.1 surround sound audio quality. The technology, titled XM HD Surround, is the result of a partnership between XM and Neural Audio Corporation which provides content with six discrete channels of digital audio. The former XM Live channel also broadcast in this format for certain concerts and studio performances. XM manufacturing partners such as Denon, Onkyo, Pioneer Electronics (USA) Inc., and Yamaha introduced home audio systems capable of playing XM HD Surround. It is not known if the XM HD Surround technology is used on the service as of 2015.