Looked at a ZIP code-based report to get a general idea of the situation. This is hill country we're talking about, so a location-specific report, either by street address or coordinates, is especially crucial for your situation. In the meantime, here are some very general ideas:
VHF stations are 7, Boston; 9 Manchester, NH; 10, Norwell, MA; 11, Manchester; and 13, Providence RI. Manchester (9) is the nearest at 35 miles, and most others are between 50-60 miles. This is fringe reception, where a UHF Yagi simply won't cut it for channels 7-13. The best add-on VHF-high antenna you can get at reasonable cost would be the Winegard YA-1713. If a single, all-channel replacement is more to your liking, you're a good candidate for the Winegard
HD-7698P.
What make and model pre-amp are you using, Dustin? The two strong stations nearby -- WUNI 27.1 (RF 29, noise factor 58.2
dB) and WUTF 66.1 (RF 27, NF 52.8
dB) -- are just strong enough that, together, they would probably overload most full-power pre-amps. Too much signal is just as bad as not having enough. When you pulled out all the pre-amps, you experienced the "not enough" part.
For a similar reason, the distribution amp is, to be honest, overkill. Few homeowners need more than one or the other, and you're definitely in pre-amp country. Have you tried the system by replacing the distribution amp with a splitter, and just running the pre-amp? (I know you said you had "replaced the amps one at a time," but that might mean something else.)
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