The Digital Media Association, which represents companies with major music streaming operations, and royalty collector SoundExchange have agreed on a cap for some webcasters. The cap applies to the $500 per channel minimum—no matter how many channels or stations were being streamed—established by the Copyright Royalty Board earlier this year. Instead, members of DiMA offering more than 100 channels who go along with the agreement will have a $50,000 cap on what SoundExchange calls “the advance against royalties.”

In return, starting six months, the companies have agreed to provide a full accounting of songs played (24 hours a day, 365 days a year). The two groups also will set up a committee to examine the issue of “streamripping” and potential technological solutions. DiMA members include Microsoft, AOL (NYSE: TWX), RealNetworks (NSDQ: GOOG), Yahoo and Pandora. Negotiations continue. Releases: SoundExchange, DiMA.

It’s only one step with many more to come. Wednesday we wrote about the deal SoundExchange is offering smaller webcasters. We heard from him today. His detailed explanation about why he’s rejecting the offer is in the comments to that post. One point: “But even not counting the international listeners, at the rate we’re growing in 12-24 months we’ll be over the usage cap; and have to pay at the higher CRB rate for all the listeners we have over that amount AS WELL AS pay the percentage of revenue royalty. So we’re ‘double-taxed’ if our audience is over a certain size. “

AP:  Pandora founder Tim Westergren: “That $500 per channel minimum was kind of absurd and the truth is everybody knew that. But the real meat of this is the (royalty) rate, which has not been figured out yet.”