Antenna advice is properly based on your exact address rather than your ZIP Code. If your ZIP Code accurately represents your signal environment, then you do not need a pre-amp. If you are using an amplified UHF antenna, then I would say that you have the wrong UHF antenna.
GroundUrMast recommended a good economy full-band VHF-only antenna in the CS600. This preserves your amplified UHF antenna. I recommend that you replace the amplified UHF antenna with the
AntennaCraft 5884 for $42.99. This is a full-spectrum (2-69) economy VHF/UHF antenna.