An external sound card is not absolutely necessary for the MMX 2 or MMX 300. However, a good sound card is recommended for operation on a PC.
However, nowadays very respectable results are achieved with onboard and USB sound cards. For optimal listening enjoyment, an up-to-date high-end sound card is advisable depending on the individual’s sense of hearing.
When purchasing such a sound card, please ensure that it has surround sound technology for headphones or headsets, e.g. Dolby Headphone.
If you are considering purchasing the beyerdynamic Headzone H1, your sound card should additionally have a digital output and the "Dolby Digital Live" or "DTS Interactive".