Jay Luong - AudioBacon.https://audiobacon.net/2019/07/12/periodic-audio-nickel-headphone-amplifier-review/
"The Periodic Audio Nickel ... promotes an emotional response. Which is virtually nonexistent otherwise. The point of buying all his gear is to enhance the emotional connection to our music. The Periodic Audio Nickel achieves just that."
Gavin Phillips - Make Use Of.https://www.makeuseof.com/periodic-audio-carbon-iem-review/
"The biggest difference you'll note when switching between your regular headphones or earbuds to something like the Periodic Audio Carbon IEMs is clarity. Every single part of each track you listen to sounds like you're hearing it individually. The mixing for each layer comes through crystal clear, and you'll begin to hear different parts of tracks you've listened to already."
Dan Cohen - Gear Diaryhttps://geardiary.com/2021/06/01/periodic-audio-rhodium-dac-review/#google_vignette
""That may be the case, but I am writing this while the Periodic Audio Rhodium DAC is plugged into my iPad Pro. Not only is the Rhodium working without issue, but the sound is far superior to anything I have heard using wireless headphones, and it completely demolishes the audio from the iPad’s speakers."