Seems to make sense to me, just make sure whatever you are tapping your speakers can be supported by your amp. (I typically give it a 2.0 Safety Factor for power.) Try to avoid sharing outlets of your audio system with anything else (like PC or other appliances.) If you do, you may need one (or more) ground loop isolators https://www.amazon.com/PAC-SNI-1-Noise-Isolator/dp/B000K50HJE/ref=sr_1_3?crid=VXXU83M8Y6CP&keywords=ground+loop+isolator+rca&qid=1572640221&sprefix=ground+loop+is%2Caps%2C137&sr=8-3

Good luck, building a speaker setup, like a PC is a great learning experience!