I Need an XLR Digital Cable.

Q1. Has any one started with a $20-30 one then later tried $100 cables and see a (big) jump in performance? I’d like to hear from those whom actually did the A/B tests. 

Q2. Should I start with the under dog, no name brands, hyped or should I start with big name brands’ entry levels? 

I’m using 1 analog XLR cable as a digital cable from MIT MI-330 to play/ verify the benificial of having a DAC .... and it sure is. 
(Ayre cx-7 CD player only provides 1 XLR as digital output source. )