I tried to use a Schiit Saga preamp (unity gain) with their Aegir power amp which is on the low side of amp gain. I had to turn the volume up to near max on most recordings to get an average listening level.
The Sega has no gain, your source has to be high voltage such as a CD player to drive an amp with enough voltage. If you were hooked to a low voltage source like a record player, you would run out of steam. And that is why active pre-amps exist.