So why exactly did we name a category "Standard Power Amplifiers"? Well, because we couldn't think of a better way to describe them. We decided that any pro audio amplifier that used a heavy transformer should be called a standard power amplifer. This is not to suggest that there is anything wrong with these types of amplifiers, it is just that they are usually very heavy for the amount of watts they pump out.
These pro audio power amplifiers do have some redeeming qualities, such as their ability to slam subwoofers so hard, you'll lose your train of thought. As you can guess, these are perfectly fine if you have a bunch of roadies who can throw their back out instead of you. They are also just fine when you plan on installing them in permanent locations where constantly moving them around is not a problem.
With some exceptions, these power amplifiers are typically class A or Class A/B.