If everything is fine from the cartridge to the preamp, start switching wires from the output of the preamp to the input of your amp and see if the reduced sound moves. If it does, your preamp needs attention
Problem vith VPI Scout and Dynavector 20XH
I have a VPI Scout with Dynavector 20XH cartridge, and after setting up the tone arm and cartridge according to the Scout manual, I noticed that sound was coming from only one channel. I looked closely and could not find any bad connections. When I touched the white cable at the cartridge I could hear a loud hum coming from one speaker. I checked the ground and they were well tightened, but I still head the loud hum when I touch the white cable. When I rub my finger on the needle of the cartridge, I did not get the usual loud sound from the speaker, I had to turn the volume up high before I could hear anything like buzzing sound when I touch the needle. The turntable was working fine before, all I did was to set it up again and adjusted the height of the tone arm per the manual, then this problem stared. Any ideas?