Should sound great! And definitely wallet friendly...
The 7000s are top-quality phones and deserve a good amplifier. The x5 is portable, so that's cool if you need it, although I can't see wearing the 7000s in the subway. But I would really try to get something better like a Woo Audio, or Benchmark. You're lucky to have a pair of those phones. Very hard to come by and much better than anything Denon's putting out now.