Yeah, I thought it could be the issue with my M5, but its not.
The GROM MP3 Adapter worked, but it only had sound on one side. Plus some features that were promised by GROM did not work. Once I remove the GROM Adapter and plugged my CD changer back, I had sound on both sides and everything worked like is should. Even GROM representative confirmed that it was a bad DSP.
The DICE MediaBridge from BSW had sound (woman's voice ONLY) on both sides, but it would not recognize the Audio Input (Flash-Stick with MP3s). BSW also confirmed that was a bad DSP. I have not removed the DICE yet out my car, since I was under impression that BSW would be able to provide a new DSP in timely manner, and I did not want to do same work twice. I am pretty sure that once I remove the DICE and plug my CD changer back, I'll have normal sound and all feature will be working.
Right now, I am waiting for BSW to provide return instructions, which I have not received yet. I figure I'll give BSW until he end of the week. If return instruction are not provided, I'll have to file a dispute via PAYPAL.
Sorry, I could not help with comparing GROM vs DICE.
Its sucks that my CD to MP3 conversion did not go well. But I just got a great deal on 2 tires - 255x35x19. So I look it this way; sometimes you win and sometimes you loose.