Here is a cheap midibox alternative we found on eBay that has worked just fine for us. 

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

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.