As something to check: make sure all the Windows audio mixer settings across the board are set so that everything is working at 16 bit 48 kHz - DSD+ will only decode properly if you're feeding it audio based on those parameters, you'll have to go into the Windows mixer (right-click the speaker icon and choose Playback devices first), double-click each device listed (can't hurt to make sure everything is working on the same basis) and for each device make sure the Advanced tab shows the Default Format is 16 bit, 48000 Hz (DVD Quality) for
every device.
As a tip: I'd suggest using
VB-Audio Virtual Audio Cable (a donationware product) instead of what you appear to be using (Virtual Audio Cable, a commercial product). It's not about the price, mind you, there's a chance you paid for VAC and find it useful, but in my own experience the fact that it's not a simple "install it and go" product which does require some configuration which has to be very precise often causes more problems than it's worth. VB-Audio Virtual Audio Cable is very simple: install it, and... well that's pretty much it aside from making sure it too is set for 16 bit 48 kHz operation in the Windows audio mixer.
I spent an hour working with VAC in the past (I know it has a trial period so I did that to become familiar with it to help others) and found it lacking and just not worth the hassles and the configuration necessary.
For me, VB-Audio Cable just works, period, and I've never had an issue with it. On a clean machine that has never been used with any SDR software or hardware at all I can install the Zadig drivers for an RTL stick, VB-Audio Virtual Audio Cable A (since only one is required but there's a second one, B, also available if needed), SDR#, Unitrunker, DSD+, and be monitoring something -even digital comms - in under 3 minutes and I've done it several times for other people - it's shocking that it can be that "easy" to them because they'll probably have stumbled along with instructions from 15 sources and it confuses them which is understandable.
Of course I've done this so often these days it's second nature to me so I can't blame people new to using this software and hardware if they're having issues, most of the instructions out there are lacking pretty severely so, asking for help is obviously a necessity in these kinds of situations.
Anyway, the two tips above should prove useful, at least that's the hope.