In my opinion, it depends on what kind of cartrdige you want to use.
If you want to use a moving coil cartridge, you'll definitely a phono amp for better and louder sound. But you settle for a moving magnet cartridge like myself, probably you don't need one. Actually when I've tried a moving coil cartridge without a phono amp, I could barely hear the sound from the record. But with the moving magnet cartridge, the sould was much louder and clear. I think you can get the same effect if you find an efficient phono headamp with a higher S/N dbl. I've an Ortofon MCA-76, but its S/N dbl is rather low, compared with modern models like NAD or Cambridge phono amp. I'm going to put it on ebay soon.
Currently, my turntable gear is Linn Sondek LP12, a vintage gear,
with Shure V15III moving magnet type. Marantz amp, Mcintosh C29 preamp.
It sounds great, especially for jazz on my gear, JBL 4343.