NAD C355BEE Owners - Advice Needed

One of my friend who purchased a used unit few months ago noticed from the user manual that there are links provided together with the amp that shall be connected between the Main-in and Pre-out sockets in normal use. The links were not found in the box when he got the amp.

The question is do the links really need to be connected between these sockets at all times even when they are not in use? How do these links look like? Are these a metal connector or a piece of short wire?

For users of the C355BEE, the user manual page 8 item no. 12(Pre-Out 2) and item no. 13(Main In) states "In normal use, these should be connected to the Main-In sockets/Pre Out 2 Sockets WITH THE LINKS SUPPLIED".

I have sent an email enquiry to NAD but have not got any response from them. Personally I reckon there wouldn't be any issue without the links but just wanted to be sure. Any advice would be helpful. Thanks in advance.
Here is a picture of what they look like on the C355BEE:
Thanks. That is one clear picture of the C355BEE's rear panel. I need to get back to my friend.
It's likely that the previous owner was using the NAD as a preamp or a power amp along with another component or used the outs to wire a sub woofer. One would have to remove these links in order to take advantage of this great feature the NAD offers. If you are using the unit as an integrated amp you do need these links. I am surprised NAD does not offer replacements at a reasonable price! The other links perviously mentioned all will work well but are a little costly.
That's the down side of buying used gears.

You think you got the savings with used gears but then again it depends.

Most sellers here are honest and quite courteous but some apparently are not that nice or sometimes are too lazy to find things for you.

Agreed with Knownothing, Audioquest is noticeably better than the factory cheap metal bars. But there are other places that you can order the pre-amp jumper cables like the places mentioned by Knownothing and Dr.Dennis

Dr.Dennis had a good idea. Why don't you order both brands online? Keep the pair that sounds better to your ears and return the other pair.

I paid $50 plus tax for a pair of Audioquest Copperhead about a month ago for my NAD C326BEE at a local B&W dealer.

Don't pay more than $60 for a pair of pre-amp jumper cables.

Online purchase may save you some $$$ in this crazy economy time.