A portable computing device having a substantially non-conducting outer housing and alternative electrical grounding and audio system architectures is disclosed. The device can be a laptop computer having a main logic board, a keyboard assembly, an audio source positioned below the keyboard assembly, and an equalizer electrically coupled to the audio source, with each of these components being electrically coupled to a universal grounding structure. The audio source emits sound waves that are propagated through the keyboard assembly and between gaps between keyboard keys and the outer housing. Settings for the equalizer can be selected to account for sound absorption and amplification characteristics of the sound waves along these sound transmission paths. The universal grounding structure includes a plurality of separate ground components that are electrically intercoupled, each being substantially smaller than the overall portable computing device, and also includes an electromagnetic interference shield around the main logic board.