Total novice question here. I just finished watching a YouTube video where a guy made an amp using ice power boards from parts Express to build an amp comparable to/ with the same components of highly regarded companies costing much more money. My question is regarding input/output stage as reviewers of audio equipment are always dissecting the input output stage of stereos and I'm wondering where is the input stage or signal processing in these homemade setups? Is it all on those boards available from parts express?