Basic cable question

Of course he told you that.  He's...the...Transparent...salesman.

Seriously, some argue for loom consistency throughout, but the majority don't go that route.

It's good the you can see right through him.  
Like said, you don't need to stick with the same brand. 

All the best,
Nonoise

Truth be told:
I fell into the Transparent void early into my reintroduction to hifi after 30+ years.
Here is what I learned-
Cables are very system dependent. What works in one system might not in another.

Since I don't know what equipment you are using, then it would be impossible to gauge if Transparent cables would be a positive choice for you.
What I can say is that there are very many choices (and God knows you'll get a myriad of responses here on Audiogon), that will provide you with similar or possibly better results at a more reasonable cost.
So, please let us know what you are using. It would help narrow down the choices... Well, maybe....
Bob

Lol! What a crock! Salesman is right, he is selling you not helping. 

If you really are running the stock crap patch cords that come with components then yes, anything and everything will be a major improvement. But do not just buy the first thing you hear- and definitely do not buy anything from that salesman, or any other for that matter who tries to tell you anything even remotely similar. Also don't buy based on technical BS, engineering or design BS, or anything other than what you yourself hear.

Speaker cables, interconnects and power cords are components in their own right. They don't need to be the same brand any more than your amp and turntable, or speakers and power conditioner. 

With all components but especially cables you should never buy what you haven't heard at home in your own system, or at least not without a 30 day no questions asked return policy.  Even then never buy what sounds the best until you have tried several contenders. Especially with cables. There are so many and the range between merely good and outstanding, you won't believe until you hear it for yourself. Which will never even happen unless you try a lot.