Personally, using but one source? I'd step up there first. Briefly using the Pro Sils, I wasn't terribly intrigued with them. They arent too refined. In combination with that Bench DAC, that right there might be the issue.
If only one IC is in place as main and source IC, I should think it ought to be a very good 'un.
Before exchanging spkr cables, I would try a Cardass NR in place of the Pro S... or better still, the HT Magic I. Maybe the Magic II, but maybe not. I have always gotten the impression the Benchmark doesn't have the friendliest top end to begin with, but can't really say, not having had one of my own.
The NR = $250 or so, and the older Magic I = $300 or so. Both would be a step up over the Pros.
Another IC that would help is the SR Resolution Ref x2 active. it is better than the C NR, and in some respects the Magic's too. In fact those wires as spkr cables ought to do you quite well all by them selves.
I just sold a pair of the ICs for $420.
Another IC worth investigating to elevate your sonic quotient would be the Nirvana SX Ltd. As spkr cables they'd be too costly.
SX Ltd = 650 750 depending.
The Nirvana SL as spkr cables might be worth a look see too, call the cable co and give a few sets a try out in your home... but only one set at a time... and take notes.
The Nirvana SL will tame any top end. They are the smoothest wires Ive ever heard
let me say that another way
theyre the most listenable wires Ive ever heard. Had I known about them when I had my KAV 250 + Montior Gold 60s, I might still have them.
As I use a preamp, I want my spkr wires as neutral as possible. I apply ICs to sources so as to better accomodate the sources needs and my preffs in order to reveal as much info in a well heeled manner as possible.. too much info provided to starkly is simply too much.
Yeah
Im not a dead on neutral all the time sort of guy. Im closer to it today than ever before, but still hang onto the warm side of it more often than not.
BTW my main IC is a HT Magic II. spkr wires are SR Sig 10 x2 active.... they're neutral and have worked well with every wire I've listed here and several more, and on several speaker types. I paid $600 for mine I think.
Another way to add to, and tame top end energy or brightness is with a nice digital pc on the DAC
. Just a thought.
Lastly
as much as I didnt care for the Pro Sils, they arent strident or bright IMO, just not whats possible for a little bit more as from the Magics for instance.