Can an audio sample be used instead of a VCO to initiate a patch and if so what module would be needed to to convert the line level signal into one loud enough to be used in a modular setting?


You will need a module that can play samples (like Disting Mk3+ among many others). The module will take care of amping the sample to modular level. If you just want to get external line level audio into your rack for processing, a amplifier (+20 db) module is needed.


Also, in some cases you can do the conversion/editing of the sample on a computer, then transfer this via means other than audio to something that can work with them. Several sample playback devices make use of SD (or micro) cards to store and transport samples, such as Tiptop's ONE, or you can move the sample via USB to some of these; Waldorf's NW1 is capable of this, as well as interconnection to edit/manipulate sampled wavetable data. It sort of bridges the divide between 'sampler' and 'oscillator', actually, being an outgrowth of the PPG wavetable engine.