Focusrite do not have an audio demo of the Liquid Channel although a CD has been made independently of Focusrite which contains clips of the LC emulations:
Lynn Fuston of 3D Audio, producer of the '3D Mic', 'Preamp', and 'ADC' comparison CDs, recorded the results of his review tests as 24-bit, 48kHz sound files, resulting in 3D Audio's latest comparison offering 'i, emulation - the liquid preamps'. In addition to comparisons with seven analog preamps, there are also samples of all 40 of the preamp emulations included in the Liquid Channel. There are 69 WAV files in all, which can be loaded into any DAW for easy A/B comparisons. The 'i, emulation' CD is available for $19.95 (+s/h) from 3D Audio.
Alternatively if you would like to demo a Liquid Channel then please contact the distributor for your country (contact details can be found in the distributors section of the site).