I recently aquired a Dynaco ST-70 and a pair of Quartets. When I turn the volume up with the Dynaco running through the Quartets, it sounds a bit "bright" or "harsh." However you describe it, I am disappointed by it. The Quartets sound smoother at high volume with my solid state amps (Carver m1.0t, Yamaha A-1020 integrated, or self-assembled ebay JLH 15 watt class A, Toshiba SA-775 reciever).
When I run the Dynaco through my KG 4.2s, it sounds better to my ears. It sounds warmer, more "cohesive," and less harsh. I notice this most easily with female vocals, but it seems to be there with everything.
I am currently using an Onkyo TX-8050 as a preamp (with a Little Bear phono preamp) and wonder if a different preamp would help. I use the Onkyo as a preamp for the solid state stuff though, so I'm not sure that would help.
Does anyone have any suggestions for making my Dynaco-Quartet combo sound better?