A great interconnect between Soulution 751 and 725

How much is the total price of those two units ?
2K $   is not much for these highend gears.

I have once owned Soulution INT 330      
The high frequencies were a bit strong with AMT tweeter.    
Depend on your speakers . ´´ warm ´´ cables would be to consider.

I'm a fan of Acoustic Zen Silver Refererence II.

I don't think you can improve much by going up in price from here, except more marketing, packaging, and cosmetics.

Jerry

In my view, your best upgrade is to take advantage of your components' balanced design and connect them using balanced XLR cables.

+1 @maxwave 

The quality and transparency of the Soulution components are one of the best in high-end audio so that lower quality cables would bottleneck its performance. I suggest starting at least to the level of Siltech Classic Legend level - this is what I own and my electronics are near the Soulution 3xx entry level while the 7xx is their top of the line.