Good old Audio research LS-7 on bench
This is the one of Audio research gems from middle nineties, with all tube simple two tube per ch circuit, no micro controllers, no remote features , just simple mechanical input selector switch, and high quality volume control.
We take it apart, clean it thoroughly and replace components in power supply and audio circuit, fine tuning & upgrade of sound quality with new selected caps was addition.
Tubes were also selected IN CIRCUIT, not only on tube tester, but in circuit of this preamp, for best performance inside this very preamp.
