Here's one place that's done extensive work on them:
I run my Benchmark directly to my Bel Canto digital amp. I recently changed the hookup of my benchmark from the unbalanced RCA side to a balanced XLR connection. I am stunned at the difference. The music is much more vibrant and alive. The improvement in the soundstage is also huge. This is coming from someone who is generally sceptical of cabling and tweaking items. If you have the capability to run your Benchmark through its balanced side try that before you mod it. The XLR interconnect I used is a DH Labs Silversonic.