I tried two different variable amps (1- radio shack and 1-??) and neither of them was worth snit. I varied them from min to max, filter out/in while watching the picture as it went from very bad to horrible (noise-snow etc). Both amps returned. I tried non variable radio shack amp (10db ??) and picture looked pretty good (big improvement), tried Philips 12db amp (walmart-??) and it looked even better (radio shack went back).
I use ATT cable, expanded basic (was TCI) to 4 cable ready tv's (two 20 inchers, one 20 year old nec 26 inch, one sony 36 inch xbr)and 3 replays. The cable feed is into a four way splitter outside the house then outside wiring to two bedrooms, an exercise room, amd a rec room. In the bedrooms and the rec room the feed is then split 2 to 1 between the tvs and the replays. I drilled some more holes and ran the main feed into my house through the amp then back out and into the four way splitter.
The picture with original TCI setup (well before replay #1) was very bad; had them out several times. Basic / expanded basic stations that were tuned by their box had grain bigger than Kansas (HORRIBLE), I found that by using the tuner in the tv (xbr) picture was drastically better, the other sets were also much improved; some stations i/e 95 was pretty good 3 was still poor but greatly improved over their box and the rest were between these two in appearance. The digital stations (premiums) all had soft focus, some better many worse (none looked as sharp as 95 on the xbr using the tv's tuner), plus regular pixilation problems on many digital stations often occurred (overcompression ??). TCI replaced their box and god knows what else but they never got it looking good (I may have been more critical after getting the 36 inch set).
Eventually I dropped the digital service, and just kept their expanded basic service. Got dish network for premiums only (in rec room and 1 bedroom), and got drastic improvement over what tci digital cable premiums had been. The basic stations stayed pretty good to poor.
Then I started with replay (and splitting the signals further), picture got below my tolerable levels again so I started trying
to amplify it. I never got one of those expensive amp/splitter combinations because the splitter is outside in the rain/snow/etc. Of the four amps I tried, both of the fixed amplification ones produced very big improvement, both of the variable ones were so bad I wonder if their variable nature is introducing a problems or if they were both just bad.
Anyway with my present "el cheapo" 12 db amp and 7 drops the picture is much better than it had ever been, it's also better than any of my neighbors. Channel 95 and many others are excellent(amazingly so), most are very good but channel 3 (cbs) and a few others could still use a little improvement. Perhaps if I find a returnable 15 db amp with no shipping charges (local purchase) I'll try another.
Anyway, try one, try a bunch, I think it's all FM anyway.
Good luck
Tommy