Speakers cut out and so does amp

I have a 1995 nissan 240sx.  I only have the front speakers hooked up, with a pioneer p7600 cd player, kenwood kac-929 amplifier and a audiobahn awt10x.  The problem that I am having is when I turn the volume up past 15-20 the amplifier cuts off, but then will cut back on after a little bit.  The more bass a song has, the sooner it cuts off.  And another problem that I am having is if I turn the volume up to 20-25, the sub keeps hitting, but the sound in my speakers just shut off.  So all I can hear is bass and no words.  The amp is somewhat old, but at the same time I think that I might be pushing it too hard.  The  only thing is, that I have had this amp for awhile, and it worked great for awhile and then started cutting out.  I plan on getting a new amp, but am just curious what could be the problem.  Any suggestions would be a great help.

One of two things is happening: the impedence load on the amp is too low, and/or your input gain is too high.Support the12volt.com

Your speakers may not be able to handle the amp....