My new tivo Bolt works perfectly fine with OTA antenna. However, i wanted to add cable so I had xfinity-comcast cablecard installed yesterday (technician indicates signal strength is perfect) but the bolt has major pixelation in standard def and can't even pull in HD channels. The tech initially installed an amplifier on my coax network and tested around 0db on every channel. House and wiring is almost brand new. Haven't tried going w/o the amp. Suggestions?