I own in my collection, an RGR model 3 and a model 4 ( I had several RGRs, but sold those ). These sound, imo, very tube like. I did some mods on them, and for an inexpensive preamp ( sold for around $900 when they became available ), a good unit. I however, removed all preamplification from my main system, as the high sensitivity of my speakers allows my dac and other sources to drive every amplifier I own ( and some I no longer own ), with aplomb. Every preamp, ime, does " something " to the sound. I will not question those that use a preamp, as I understand why. But for me.....?