I "think" that the VAIS SL3B will provide A2DP audio streaming on your 2005 SC430: http://www.vaistech.com/site/sl3b.php
There may be other companies that have products that will work but VAIS has been around time and their products were commonly offered by Lexus dealers before Lexus vehicles came with similar interfaces from the factory.
I suggest that you contact VAIS and inquire before you buy. They may have other products that would be more appropriate for you.
I performed this fix and now have no power above the clock. The AC/Heat doesn't work, nor does the display. Has anyone had this same issue or would you have any suggestions? I have checked all the connections numerous times and I have also checked my fuses. Any advice would be appreciated.