I contacted Radio Shack through its web site a couple days ago and got this e-mail response/reply yesterday:
"Date: Sat, 7 Jul 2012 15:35:06 -0400 (EDT)
Subject: Re: I need help finding a product
x-mailer: KANA Response 126.96.36.199.6
Thank you for contacting RadioShack.com.
We appreciate your inquiry and would be happy to assist. After careful
review of the products you've included in your questions, we believe we
have located all the information you require.
Our review indicates the products both do not work as a
pre-amplification device for your coaxial cable signal. The catalog
number 15-321 boasts a amplification of 40 decibels while the catalog
number 15-259 indicates the amplification is approximately 20 decibels.
At this time we have been unable to determine the measurement for
additional noise potentially generated by the devices..."
So it confirms that these amps are not for what I need for my situation.
Ugh, I will have to keep searching for a local Los Angeles/L.A. area store with pre-amps.
A newbie question: Do all pre-amps require power connections? Or are there actually pre-amps that don't require it? The reason for this is because the attic where the coax cables and splitter to the outdoor CM-4228HD antenna does not have a power outlet.