XLR cables, worth buying higher end?

It really depends on you equipment, your ears, how critically you listen. You need to have a pretty good system to notice. Now, it will be noticeably louder... but not necessarily a noticeable difference in quality. The volume increase makes it really hard to compare for quality.
.
I used single ended for 40 years. It was only when my system got to really high level of performance with all ARC stuff... who recommended using XLR as the have all balanced internal design that I finally converted. 

Yes and...

I noticed the use of XLRs result in increased signal level versus RCA.

The basic (better cable and mogami) versus higher end (kimber) was noticeable for my source components.   The impact was less than the RCA to XLR.

XLR lowered the noise floor on my Pass XP-20 to XA100.5's. I wouldn't spend to much to try and see if it makes a difference on your equipment. I used these https://www.dysonaudio.com/collections/facemelters.

Problem is i need two xlr pairs since i am using a stereo tube preamp bypass between a processor and speakers.

my system is revealing.

I have been completely satisfied with balanced interconnects made with Mogami W2549 cable and Neutrik XLR connectors. These can be made up for you by many pro audio shops. Last time I looked, a pair would be considerably less than $100. You might even get both pair for that.

I had mine made up by ProAudioLA.
I compared them to some expensive name-brand cables with glowing reviews. To do that, I ran single-blind comparisons with four friends, each separately. We all found the expensive cables to be noticeably more colored.