could be either. Chinese parts in amps do not last long. depending on useage, it could be 1-3 years, or as long as 5-7 years. but they certainly do not last as long as USA, Japan, or German parts.
the drivers from a lot of the ID companies are questionable. while i am not familiar with Epic's drivers, quite often it is the driver that takes out the amp.
for a lot of companies, it is more important to make a huge profit, then to offer a quality product. problem is, we have been regulated to accept low grade products because of the prices we expect to pay. cheap or good... you normally cant have both. but i have seen a trend towards expensive and lousy unfortunately.