Regarding whether to choose the high or low setting on the circuit this will depend on your system. If your volume display on the calypso is low (less than 30 or 40)to get the playback dB levels in your room you would be best to try switching to the lower gain setting. This will also reduce tube noise as you noticed.
Go slow on tuning the preamp with your system. As mentioned above the 12ax7 tube has the most effect of the sound and by rolling this tube you can really tailor the sound to fit your mood. Two experienced dealers for this unit are Andy at Vintage Tubes for old stock selections and Jim McShane for the wide selection of current tube offerings. Both can help you get the Calypso to sing.
Go slow on tuning the preamp with your system. As mentioned above the 12ax7 tube has the most effect of the sound and by rolling this tube you can really tailor the sound to fit your mood. Two experienced dealers for this unit are Andy at Vintage Tubes for old stock selections and Jim McShane for the wide selection of current tube offerings. Both can help you get the Calypso to sing.