I teach cardio classes in different locations and want to purchase a portable sound system with good quality around $250.00. I want to understand the specs I need to look for when researching. Watts, woofers, etc. How do I know by the specs on the web that it is a good system, will be loud enough, and have good quality sound without distortion, and the right size for my classes? I will need to add a higher quality mic system in the future so the speaker system needs to have plug ins for mp3 and mic receiver/transmitter. And be totally portable.