Splicing isn't a great thing for video, but probably better than running wire down the outside of the house.

Anytime you splice a signal cable, there's change in the impedance of the cable at the splice point, which results in a reflection. The better the splice is, and the closer the cables are matched, the less of a "blip", and the less the problem. Best case would be 2 cables of the same model number from the same manufacturer.

With random RG-59 and random RG-6, I'd guess you'd lose about 1.5db. (That's a guess, I'm used to working with radio stuff, not cable TV) So anyway, the loss of the mis-match should be quite a bit less than the loss from a splitter. More important is that you'll be cutting the signal strength to the devices that cable feeds by slightly more than 1/2 because of the splitter.

What's critical, though, is to figure out which side of the wire the signal is coming from, so you can put in the splitter correctly. It might work backwards, but it'd be lousy compared to the right way.

You'll be changing the balance of what could be a well designed TV distribution system. Often the cable TV setups are lousy anyway, and the cable company just pushes the signal up enough to compensate for the loss.

At least one exception to all of this is if they're running a cable modem for Internet. Those require such a good signal that adding a single splice or splitter can sometimes break them. The line to watch is the one running from the pole to the cable modem - don't splice that one. Anything that's already split off of that can be split without interference. Digital cable may be the same thing, I don't know. If so, it would be the same concern - the line from the pole to the digital cable box(s).

Use a good quality splitter. There used to be some really cheap ones out there, don't know if there still are.

"While I'm ranting about CAT5....." [Linked Image]

I'm glad it's not just me. Every once in a while I see both CAT3 and CAT5 correctly used for a drop, and it always gives me a warm fuzzy feeling.