Best XLR IC's for around $300/pair?

There's a pair of Acoustic Zen XLR Silver Reference II for sale here now. A bit over your price point but perhaps negotiable. They are nicely detailed without going too far and also do great with tonality and imaging/soundstaging. In short, a great all around, well balanced, and neutral interconnect. Best of luck.

You can also typically pick up a set of Harmonic Technology Pro Silway II's for about $200 a pair in XLR's. Quite a nice cable.

I use 2 pairs of AQ XLR Diamondbacks bought used. My preamp to amp run is XLR but not balanced, and Mogamis from Guitar Center (seemed like a good idea since I've used their mic cables for years) sounded extremely harsh in that position (note I have Mogami Neglex from my TT and they're fine) so they were returned to the knucklehead store (manager says to me: "You don't need break-in since they're pure copper"...OK then). The Diamondbacks are a neutral sounding bargain and an extremely well put together cable...solid core with tough XLR plugs...I use a run from my DAC to "balanced in" on my preamp also. Bungees...they're bungees...