Welcome aboard ChuckF!
We have a Sony TV that randomly goes to 100% volume. No great loss if the crappy little speakers blow up, but the TV is routed through the AVR so we have to be quick with the kill switch. I didn't find anything obvious, but does the Rotel offer an option to limit max volume?
I have experience with the SHD. The folks at Deer Creek Audio (where I bought the SHD - highly recommended) will tell you they have customers who use nothing more than the SHD and Hypex amps they also represent as their core system. I think the SHD is perfectly capable in that roll, especially if you're looking for something to build on with DSP at its core. Your satisfaction will likely depend on your vision and preferences and honestly how resolving your system (room included) is and how perceptive your ears are to nuance.
I bought it primarily for its DSP functionality but, given some reliability problems with some gear I had at the time, I opted for the SHD over the Studio to serve as a one box streaming DAC / pre amp backup. It's a perfectly capable all in one solution, especially if you want to apply DSP to your analog sources. But in my experience it really shines as a digital hub and for its DPS functionality. A tinkerers playground, it is ridiculously capable and flexible. I'm parting ways because I never really warmed up full function DSP and am finding that I don't like to tinker near as much as I thought I might. I ultimately replaced the SHD with an Eversolo DMP-8 to reduce box count and because it includes more basic but very capable DSP. But even that I'm finding is too much and I'm finally settling into a simple 6 band Schiit Lokius for all my sound shaping needs.
Volumio is a perfectly capable streamer. If it was all I had and all I knew I'd probably be quite satisfied, but I'd already been spoiled by BlueSound so I only played with Volumio. The Eversolo streaming functionality is on par in most respects to BlueSound. I've not experienced Wiim Pro but understand it is also has excellent steaming capabilities. Again, as a digital hub, optical from your preferred Wiim amp to the SHD is provided.
It appears the SHD uses the AKM AK5574 / AK4490EQ chip set. Good stuff as I understand (same as used in Eversolo DMP-A8 and I believe AVA digital pre). I thought they used the ESS 9028 but that was apparently old news. The Emotiva lists an Analog Devices AD1955. These are just numbers to me. I prefer my system with the A8 installed but I can't point to specific reasons other than it's easy listening. Those in the know will tell you (others like me parrot) the chip set doesn't make as much difference as the implementation.
If you want to talk Schiit, I'm a bit of a fan boy and have a fair amount of experience in addition to the Lokius. In addition to a Marantz PM KI integrated, my system currently includes the Lokius, Lyr + HP amp/pre, and Aegir 1 feeding Spatial Audio M4 Sapphires. I'm still in the market for a proper pre but the Lyr + leaves me in no particular hurry. I've tinkered with more audiophile recognized names but the reality is I'll likely land on a Freya+ F. The one knock on Schiit I have is remote volume control resolution - about 3 relay clicks or ~ 1.5 dB. Forkbeard volume resolution is 0.5 dB but until/unless I update I tweak volume by getting off my butt or using the Eversolo remote for 0.5 dB adjustments. The Kara seems to be reasonably well regarded for the money and I/O but you already have a great headphone amp.
AVA is highly respected - including onboard phono stage and HP amp - and has been on my bubble for quite a long time. Unfortunately I'm shallow and prefer my gear in black. Depending on where you land with DSP/preamp you might consider a pre with multiple line outs (if your external phone pre doesn't include) so you can easily bypass DSP for your analog sources if desired using something like a Mapletree Audio LR1/2 line router or Schiit SYS. As I understand it, the mini DSP SHD doesn't have an analog bypass - which make sense given its mission.
Good luck!
