Here is a cheap midibox alternative we found on eBay that has worked just fine for us. http://www.ebay.ca/itm/361579702907?euid=6e99146ae9f84ea2ba7b7c0bad927f50&bu=43001921709&cp=1&sojTags=bu=bu
We haven't tested this product for noise issues yet, but it worked for midi commands.
PLEASE NOTE: There are other midi adapters on the market that look exactly like the one above, but have different connections that WILL NOT WORK with our products, like this one http://tinkersphere.com/audio/788-midi-to-1-4-adapter-5-pin-din-to-stereo.html
One of our customers had this exact situation, and proposed this solution, which worked perfectly for him. A DIY midi to TS cable! Note that it may cause noise issues with your setup. See attached pic. You create a connector where sleeve of the TRS jack is connected to pin 2 of the DIN jack (ground), and tip of the TRS jack is connected to pin 5 of the DIN jack.
So, the pinout of the DIN jack is:
TIP - pin 5
RING - pin 3
SLEEVE - pin 2