I tried these In Ear Monitors at the Sensaphonics booth and they worked great. The convention sound/hum was ubiquitous and by adjusting the monitors the outside sound was completely gone and I could focus on the volume and mix of the music. Check this out. 

3DME uses universal-fit Active Ambient earphones with embedded binaural mics to create 3D spatial awareness with IEMs inserted, controlled via a rechargeable beltpack mixer. The free ASI Audio app provides access to powerful sound sculpting tools like 7-band EQ and limiter control, using your smartphone or tablet to create a truly customized in-ear monitoring experience.