Hello and thank you all for the warm welcome!
I've had these Audio by Van Alstine DVA M225's now for nigh on three weeks, playing incredibly fun and delicious music with the new AVA amplification every chance I get. I have to tear myself away from each listening session to actually do other things in life that need doing and enjoying. LOL. It's really been THAT good. I've done a lot of work in trying various adjustments and setups and have found what sounds best to my ears for now.
Absolutely love the upscaled sound signature and "new life" that has come into my system in so many ways. I'll share some of the changes in my experience including sound stage widening and deepening, instrument separation and location, completely lack of background noise and just the right amount of clarity and brightness for my taste at both low and higher volumes - just to name a few.
I've tried both of my Ascend Acoustics speaker pairings at length, the Sierra 2EX-V2's and the Sierra-LX's. Both sound even better than I've ever heard them before - playing through the 225 amplifiers. And the addition of the one subwoofer makes that improvement even more enjoyable! 
The one downside, and an interesting one to me, is that a certain percentage of the music that I've been listening to is suddenly exposed as being poorly recorded. I hadn't heard that before in listening to many recordings that are now unlistenable (or at least a bit annoying) in any of the historical iterations of my home sound systems over the decades. The good news is that the "good recordings" are also that much better! I'd been completely happy with my system thus far, blissfully not knowing what I was missing...
Long story short, I'm inspired to move forward get my accompanying gear and other aspects of the system to match up to the improved sound-quality provided through these AVA monoblocks. I'm confident that implementing many of the suggestions ya'll have made would likely improve this system even farther towards new levels of enjoyment.
Appreciating everyone's input in regard to my first post, I am in a bit of conundrum (in a good way) and would be happy to hear anything you'd care to share in regard to my current situation.
As I mentioned in my first posting here I plan to add a preamp. Until I have the funds for that, so far I've tried using both the preouts from my Musical Fidelity M6si 2 channel integrated, and those on my old Yamaha RX-A 3080 AVR receiver. Both show starkly noticeable improvement over using their respective internal amps. I've settled in on using the Yamaha preouts.
The Yamana wins by a good margin. I've come to discover a difference through sound level matching and comparing over and over. The ultimate difference I think is at least partly due to the bass management of the Yammy and inclusion of my one Rythmik F12 SE subwoofer. Both sets of speakers sing like I've never heard them before. (no apologies Mag_Neato, your words fit perfectly here)
A couple of you had suggested adding a second (and third and fourth) subwoofer. I've considered that for a while but now can see the big advantage of that given the noticeable and enjoyable improvement via the 225's. I have been doing the math, the F12 SE sub has doubled in price since I purchased the one have now, but I'm thinking the added cost of one more sub will be worth saving up for.
What I am considering is whether I purchase the Parasound P6 (haven't really found any other viable options) for a preamp with bass management including both high and low pass filters. I also want to put in the effort to understand your suggestion Mag regarding "having them EQ'd/controlled by a MiniDSP 2x4HD with filters imported from REW." I am intrigued with going that route.
My dilema: I was counting on making my next purchase the AVA Fet Valve CFR preamp as I had mentioned in my first posting. I figure the synergy alone with the 225 monblocks would be a game changer. How might it be possible or feasible to add the tube pre while also including the extra subwoofer and the most crucial (as I see it) bass management that would come with the P6?
Considering all the options here within timing and budgetary restraints, thought I'd throw that out there if anyone would care to share their perspective or not, and again, many thanks to everyone here on Audio Circle!
I've also been in contact with AVA via email expressing my condolences on their loss of Frank, and sharing my experience with the M225's so far and exploring the options for my potential future purchase of the CFR preamp.
They have been super friendly and helpful! I wish everyone at AVA all the best moving forward.