Hackers are claiming to have discovered a way to copy music from Napster's new portable subscription service, Napster To Go.

NEW YORK -- Hackers are claiming to have discovered a way to copy music from Napster's new portable subscription service, Napster To Go.

Users of the Winamp digital music jukebox have been reporting on peer-to-peer advocacy sites like boycott-riaa.com that they can capture Napster To Go subscription files and burn the tracks to CDs by installing plug-in software for ripping radio streams called "Output Stacker."

Napster To Go utilizes Microsoft's new Janus technology, a Windows Media Audio solution that is designed to allow for secure transfer of subscription content to portable devices. The service allows subscribers to transfer an unlimited number of songs from the Napster library of 1 million tracks to a Janus-compatible device for a monthly fee of $14.95.

A Napster spokesperson says the company is aware of the issue and stresses that the technique hackers are employing does not represent an infiltration of its digital rights management.

The hackers are using software that copies music from the sound card of a computer as the music is being sent through the speakers -- a method most commonly used in recording Internet radio and other online audio streams. However, it can be used to capture virtually any audio.

Security of subscription and radio content is emerging as a new issue on the digital piracy front as a growing number of consumers gravitate to on-demand music services and Internet radio.