I think you can use a regular pre-amp without a pass-through if you set the volume control for exactly unity gain.
If you order the unit new, the factory can probably put a little tick-mark next to the volume control knob to indicate where unity gain is. Or you can take the unit to a technician.
I know of at least one tube amp manufacturer that offers this as an option.
If you order the unit new, the factory can probably put a little tick-mark next to the volume control knob to indicate where unity gain is. Or you can take the unit to a technician.
I know of at least one tube amp manufacturer that offers this as an option.