Thanks for the reply, and here's what happened today: The Spectrum tech showed up at the appointed time, and checked the signal at the 2-way splitter (a Monster Cable 2Ghz that I have been using for years). His meter (a very sophisticated device indeed) indicated that there were receive errors coming from the coax going to the outside of the house. Before going to the outside to check the signal there, he replaced my 2-way splitter with a Spectrum one. There is another 1-in, 2-out splitter on the rear of my home, with one output leg going to the splitter inside the home (the one the tech just changed out), and the 2nd output leg going to my internet service cable modem. He was still seeing errors coming from the pole, and got the ladder off the truck to access the tap at the aerial cable. At the tap, he saw a clean signal from the network, which implicated the 50-60' drop cable to my home as the source of the errors. Once he installed the new drop cable, the signal into the house was error free. We rechecked both TiVos and were able to tune SHO 1642 with no problem. Here's what I am now seeing when I run the diagnostics test on channel SHO 1642 on the 4-tuner TiVo: SHO 1642: Freq 93000Khz, Signal Strength 95%, SNR 38db. Here are the results for this channel on the 6-tuner TiVo: SHO 1642: Freq 93000Khz, Signal Strength 90%, SNR 35db. After the tech wrapped up his work and left for his next job, my wife noticed that that she was seeing some pixelation on the Hallmark channel she tuned in on a TiVo mini working off the 6-tuner TiVo. I could also see the pixelation on the the TV associated with the 6-tuner TiVo, but there was no pixelation on the TV associated with the 4-tuner unit. I also saw counting RC uncorrected errors at the 6-tuner unit. I rechecked all the coax connections and discovered that the 6-tuner's Tuning Adaptor "Coax In" connection was only finger tight. Snugged it down with a wrench and the pixelation disappeared and no more RC uncorrected errors were occurring. I replaced the 2009-vintage TA that I had been sent with the original 2013 TA, and had the Cable Card/Tuning Adaptor helpline activate the TA. I'll return the 2009 vintage replacement to a Fedex drop-off location tomorrow. Hoping for stability with my TiVo configuration, but will be keeping a close eye on it for now. Everything is working and I'm confident it will stay that way. BTW, I can see how the wiring config @mdavej mentioned above would be viable, but I'll stick with the way I have things wired now. Besides, the wife is going to be on my case if I don't get the lawn mowed before dark (in less than 2 hours from now). Thanks again to all for the comments and suggestions. Great forum!