"finish" up to 128k

Hello, All I wanted to be able to play Spec's games on the player and I ported Spectemu for it... more precisely for OpenSource firmware for players RockBox (http://www.rockbox.org) and everything would be fine, but Spectemu emulated exclusively 48k... although quickly :) .... In this regard, the question arose... where, in principle, should you dig to add support 128k? ... or maybe someone can help?