Alpine PDX-F4 4/3/2 Power Density Digital Amplifier
I'll keep it short.<br /><br />Never been an Alpine fan.  However, after installing this amp it Alpine is all I will use for my 4-channel amps going forward.<br /><br />The audio quality is best I've heard.  I've been a car audiophile since the early 90's and have followed all the changes in the industry.  This is the best (by far) 4-channel amp I've owned.  In the past I've spent over $1000 for my component amp(s) and this one sounds as good as the most pricey and is half the size.