I have been just using an AchtungAudio USB cable directly connecting it to my laptop. The Denafrips Ares connects directly into my Red Wine Audio 70.2 Signature mono block amps. I use no pre amp
Can't wait to see whether the inclusion of the USB Regen, LPS, and Curious Regen Link cable improves it even more.
How are you controlling the volume with the PC? The DAC doesn't have a volume attenuator and I'm pretty sure your mono blocks don't either.
Most people with external DACs prefer to get "bit perfect" output from their computer to their DAC. They don't want the operating system to have any control over the signal.