Are standard MP3 headphones of good enough quality?
Most will suffice. They may not be the best but they will do the job. The main thing is to be sure to use headphones of some sort wherever possible because of the way our recordings are mastered to make use of panning and crossover rhythms. However, if you want to get the very best from the HypnoDreams recordings you might like to invest in some good quality headphones for your portable device. Such as the Sony MDR-EX71 in ear headphones (Anangas personal choice), which block out external sound (the usual safety precautions, of course, apply here), are very comfortable, and are available in black or white if you are keen to have them match your listening device.