I want to build a small amp for my brother. I made this diagram using a TDA2030, my problem is my design requires a bi-polar power supply to power my TDA2030, since I only have a 220v-12v transformer would my design work, I also intend on adding a 9V PS to power my pre-amp.http://i.imgur.com/KBGaJ.jpg if this design works, what are the disadvantages of such design. Thank you :tu: