Over the years I have been able to keep my 400/4000 series 1 or 2 phase linear or carver amps up & running. There big,heavy,easy to troubleshoot,lots of room to work on,& parts are easy to find.Can someone chime in as to how the servicing is on the next generation of amps & pre amps are.PL 2000,200,3300,carver c1 etc. The units that still look like like the original units only there half the size.Thanks, tom