How does it sound? A lot has changes in 18-years; however, if it still drives your speakers satisfactorily then ther'e no need to change.
Rocky1313, I am not surprised that after 18 years your JRDG Model 1 is still going strong. My old JRDG Model 7Ms are about 20 years old. . . and the only thing I had to do to them once was to retouch the solder to the output transistors of one of the unit because of 'cold solder' syndrome. If you ever experience a dip in sound quality, call up JRDG, Jeff takes pride in servicing his amps. On the other hand, his sound has evolved a lot over the last 2 decades. Still sweet, but now also very open and transparent. Have a listen to a Continuum 500 integrated, or to a 312 stereo.