Over the past decade, Lab.gruppen touring amplifiers have been praised by renowned FOH engineers and leading sound rental companies for their tight and transparent sound. The FP+ Series model FP 4000 continues this tradition. The FP 4000's performance is based on the patented Class TD output stage, which combines the efficiency of Class D with the sonic purity of Class B. The FP 4000 also features a Regulated Switch Mode Power Supply (R.SMPS) for stable rail voltages and a highly refined circuit layout for high power density. The Intercooler technology ensures cool operation under extreme demands. The FP 4000 offers adjustable input gain and Lab.gruppen's exclusive Voltage Peak Limiter (VPL) for maximum headroom in any application.