I tried the Sleep Phones, and like Carlover said, the speakers slip around and the band creates pressure, but it was worth a shot. I need to mask both tinnitus and city noise (which I wore earplugs for before). So, now I run a loud fan, and I also picked up a pair of Etymotics and Sony MDRs. I think the Etymotics will be relatively comfortable and will stay put in my ears due to their pointy shape. They're pretty high fidelity but I'm only listening to "static" so it's almost a TOO much. The Sony MDRs have a nice noise cancellation feature that gets things quieter in the background than the Etymotics. They were cheaper but not as comfortable in the ears. Some combination of these two things might be ideal (Etymotics shape + noise cancellation) but I haven't spotted it yet...
Also the "Ambiance" and "White Noise" apps let you mix different ambient sounds together if you have a range of tinnitus tones to cover. The biggest help has been Xanax at night. As you can probably tell, I'm pretty desperate for sleep after two weeks of this plus 8 days of Prednisone insomnia--ugh!!