[GroundUrMast]

If you're happy with the channels you see now, then so am I.

Is the attic ventilated fairly well, ie. does the attic temperature stay below 120° F on sunny summer days? If so, the Channel Master CM-3410 is a robust distribution amplifier that can take a lot more input signal level than what's showing on your TV Fool report.

The amplifier has a decent noise figure... about 3 dB. And, according to the published ad copy, can 'tolerate 140° F'. It also has a somewhat unique feature, the power supply does not ship with a cord... you make one from RG-6 coax cable... so it can be any reasonable length. You would mount the amplifier in the attic, between the antenna and the first splitter. You would mount (plug-in) the power supply at the most convenient outlet... then run RG-6 coax from the power supply to the amplifier. (If the attic gets too hot, then mount the amplifier in a nearby closet. Try to keep the coax run from the antenna to the amplifier in the closet short without putting strain on the coax or connectors, keep the bends gentle, don't kink the cable. Then, if you have to, run cable from the amplifier back into the attic to feed the 3-way splitter.)

You get 15 dB gain. Hopefully, the 3-way splitter is labeled with loss values per port. Many 3-way splitters will have one output port that has half the loss of the other two. Use the lowest loss port to feed the cable going down to the basement.

I would recommend you remove the unneeded 8-way splitter in the basement. The work of identifying and tagging the working drops is well worth the benefit of eliminating 10 to 12 dB of loss from your system. Terminate any unused splitter ports... better yet, if you only need a 2-way splitter in the basement, then buy one and ditch another 4 dB of loss. (Or if you need a 3-way split, use that instead of a 4-way)

The attached drawing may be of some help... if nothing else, at least to be sure we're both thinking similarly.