I would like to play my drums to a sequencer. I want to download songs from the internet and load them into the sequencer. I plan on buying something like a Proteus for a sound source. As far as the sequencer is concerned, do I need a computer and what software is good? Or is there a stand-alone unit that would work. I would prefer a stand-alone unit if it makes sense. I know very little about this subject and would appreciate any info that can be provided. Thank you.