The microphone of the Cooler Master MH630 was tested by connecting it to my integrated sound card (Asus SupremeFX S1220 audio codec), as well as a couple of other sound cards, such as the EVGA NU Audio Pro (PCI Express interface) and the Creative Sound Blaster X3 (external USB sound card).
To review the microphone's sound and compare it to similar headsets, I used the Adam A7X speakers and Shure SRH840 headphones (both of them fall into the studio monitor category). I connected them to Audiolab's M-DAC, a high-quality digital-to-analog converter that functions as an external sound card when connected to a PC. Testing was done in Discord, Skype, and Audacity, and I also used Audacity to record the sound from the microphone. The sound was recorded with microphone sensitivity set to 100% and was not postprocessed or edited in any way.
For reference, this voice recording has been made with Rode NT-USB, a high-quality studio microphone:
This is the sound recorded by using the omnidirectional microphone the Cooler Master MH630 is supplied with:
The microphone capsule is identical to that of the more expensive MH650 and MH670, which means the microphone quality is quite good. My voice sounds natural, has a pleasant depth (none of it is being added artificially) and no hints of compression. This is a huge step up from last year's MH751/MH752. Not only that—the microphone quality of the MH630 surpasses most of the similarly priced competitors in the analogue gaming headset department, as well as many more expensive gaming headsets.
Of course, the MH630 will give you better microphone quality than the wireless MH670. They use an identical microphone capsule, but performance takes a massive hit because of the wireless connection. When the MH670 is connected to a sound card with a wire, its microphone performance is identical to the MH630/MH650. This can be heard in the samples below.