I use no active preamp with no additional gain into the amp.
Most amps do not require any additional input gain to deliver sufficient power to the speakers or headphones.
The signal level from most sources (cartridges and phono stages, CD players or transports, DACS) are at a level good to go directly into the amp.
If you find that the source signal strength seems too low (not enough volume), then perhaps an intermediate preamp is needed to supply additional gain into the amp.
All I have is the phono stage feeding into the attenuator that adjusts the signal into the amp for volume control.
Basically, yes you can use only the output of the phono stage directly into your volume control device.
If you are using a MM cartridge, then the output of the MM cartridge should have sufficient output to the phono stage.
If you use a MC cartridge, then you will need step up transformers to raise the cartridge signal to a level comparable to a MM cartridge before input into the phono stage.