I agree with Meiwan, just use the W4S as a DAC and get a nice tube integrated amp and use it's preamp inputs.
It would also help to switch to just plain copper speaker cables. LAT's Silverfuse alloy is mixing silver with copper, which will help enhance brightness and harshness. They even talk on their website about the warmth and mellowness of copper, but they "add" the clarity and definition of silver. The silver is part of the problem. It may work alright with a tube integrated amp, but you may find that just switching to pure copper cable may help alleviate much of the harshness you are experiencing.
It would also help to switch to just plain copper speaker cables. LAT's Silverfuse alloy is mixing silver with copper, which will help enhance brightness and harshness. They even talk on their website about the warmth and mellowness of copper, but they "add" the clarity and definition of silver. The silver is part of the problem. It may work alright with a tube integrated amp, but you may find that just switching to pure copper cable may help alleviate much of the harshness you are experiencing.