I have just finished building a low wattage single ended class A tube amp delivering 8 watts with a single 6L6 in output section and a 12AX7 in pre amp, both American made old stock tested tubes.
Amp is designed for harp use and especially for crystal and ceramic element microphones. It has an inbuilt reverb which can be completly bypassed or switched on. Controls on front are reverb/volume/tone.
It also has a high /low impedance selector as well as a high Low input grid stopper resitor, both helps to adjust it and adapt to differnt microphones. Some old crystal capsules like for example a much higher impedance than normal guitar tube amps have. Also has a three position bright switch (middle position no brightness), on back it has a 4 ohm speaker out and a line out. So it is a nice little grinder customised for harp.