TT4400 amp is absolutely great. The sound qality that it has put out is great. It's clean, puts out 100X4 rms @ 4ohms. I have driven my car with the music turned up quite loud for 3 straight hrs. to locations that have a temperature of 95-100 degrees and have not had the amp shutdown. The crossovers are good quality along with the customer service. My amp was missing some mounting hardware and they sent it right out to me. I also asked them some questions in emails and they responded back in a short period of time. I recomend their equipment. Their amps come with a 2 year warranty I believe and a 5 year warranty if you have it installed at a installation shop but I would ask them what kind of shop it needs to be installed at to receive the 5 year warranty if you want it.