my ethernet cable?

Margot,

If you are worried about the installation of the cable you can hire a certified cable company to test the cable with a cable scanner. There are cable installers and then there are trained certified cable installers. A trained certified cable installer would have tested the cable and supplied you with a copy of the test results.

If the installer installed CAT6 cable and terminated it on CAT5e RG45 jacks then you basically have a CAT5e Ethernet cable.

Do's and don'ts of installing CAT5e and CAT6, CAT6a cables.

Here is a video on testing cables. Note there is a lot more to testing a cable than just checking for continuity.

With a good tester the test scan will fail, if during the installation of the cable the cable was kinked. Even if the installer caught the kink and straightened it out the cable can fail the test or pass but only marginally.

If the termination of the cable to the RG45 jack was not done properly, that will show up on the test. The wire twist of each pair must be maintained right up to the point of connection to the punch down connection on the jack. No more than a 1/2" of the twisted pairs of the finished termination should extend beyond the outer jacket. Improper termination of the cable to the jack can make a big difference on how the cable will test and preform.

So you can hire somebody to test the cable for you or first just try the cable and see how it performs. It may work just fine for your application.
Jim

Margot,

IF, you have problems and the problem turns out to be the Ethernet data cable, you do not need to hire an electrician. You need to find a good low voltage cable company in your area that has trained certified data cable installers. You also need to make sure the company has/uses the proper test equipment to certify the cable after the data cable has been installed and terminated with RJ45 jacks and or RJ45 plug ends. The company should be able to furnish you with a copy of the test certification.

LOL, I noticed in my earlier response to your posted message I typed RG45 jacks instead of RJ45 jacks. It should read RJ45, So much for proofreading, my bad.
Jim

I replaced a 75' run of cheap Monoprice Cat6 that goes from my office router, down into the basement, and up into the living room stereo system with a 50' run of Blue Jeans 6a for the purpose of getting the most out of my TIDAL subscription.

The difference was very easy to detect. I'd describe the sound as cleaner, purer, and better-defined.
01-14-15: Cymbop

I believe you when you say you could hear the difference between the two cables. Blue Jeans' uses Belden cable a highly respected data cable manufacture, Monoprice doesn't say whose cable they use. They just say it is pure stranded copper. The construction of the raw cable can make a difference how the cable will perform.

I would discount the differences in length of the two had anything to do with the reason why you heard a difference, but I would like to know what you did with the additional 25' of the 75' Monoprice cable. Just guessing you coiled up the excess 25' of cable at the switch end. If that is the case, the next question would be how tight, rough physical diameter of the coil of the wire? I have found, and don't know why, that can cause errors on a PC connected to a network in the case of horizontal installed LAN cable. Testing the cable that has the excess cable coiled up in a small diameter coil with a scanner might only pass marginally. Increasing the diameter of the coil would increase the test results of the cable.

Best practices say two data cables should be installed at every work station. If you were to compare the certification test reports of a work station’s two data cables that were installed at the same time, same cable manufacture, terminated on the jacks on both ends by the same person, the cables will not test out the same. One will test better than the other. And sometimes the differences can be quite a lot with both cables still passing the scanner test.
.

Margot,

IF, you have problems and it turns out to be the cable you had installed, you could always just buy a readymade to order cable from Blue Jeans Cable and you or someone help you install it, providing the majority of the pathway is not concealed making it difficult for you to install the cable. If you do install the cable yourself be careful and protect the RJ45 plug on the end that is being installed, pulled, to the desired location. Be careful do not kink the cable. Do not step or walk on the cable as this can damage the lay of the 4 twisted pairs inside the jacket of the cable.

Pros of the premade Blue Jeans' cable?
You can save a lot of money.
You won't need additional patch cords, also eliminating two more connections.

Down side?

Physical damage to the cable at either end and or the RJ45 plug. When jacks are used on each end of a physically protected installed cable, patch cords that plug into the jacks can easily be replaced.

This may be of interest.
Ethernet LAN cable certification testing.
.

Oh, c'mon, Jea! It's just zeroes and ones -- why overthink it like that? ;-)
01-19-15: Cymbop

LOL, but unrestricted 1s and 0s are happy 1s and 0s, and therefore more productive.

Copper Cabling Troubleshooting Handbook - Fluke Networks.
.