First off... there is no such thing as a bad Decware amp.
I remember years ago at a Zenfest having this discussion with Steve.
All Decware amps are good.. it's a matter of pairing with the appropriate speaker.
And ultimately your room, your sources, type of music you listen to and your listening preferences will determine what is best for "you". Trust your ears.
After all hearing is a "perception" - an individual perception at that.
I have heard all the Decware amps and all the Decware speakers at one time or another. At Zenfest and/or in friends systems. And combinations of most of them. And I have owned a few of them as well. And a few more have passed thru my listening room or currently reside or have resided in close audio buds listening rooms. I've never heard them perform less than very good. Synergy is key though, as it is with all audio gear, and Decware is no different in this regard.
All that said, I do have a more than average amount of experience with Audio Nirvana drivers and since you have recently acquired some, I think my experiences might be applicable to you. So I'll share... YMMV of course.
At this moment, I have Audio Nirvana SCF 15" Ferrite drivers and Audio Nirvana SCF 12" Alnico drivers(I have had some others in the past). I have used both in Large bass reflex boxes of AN's recommendation and also in a hybrid Hawthorne Audio Trio open baffle. I had a Decware Rachael initially and I currently own a Torii MKIII (which honestly I may never part with). The single ended amps have their magical holographic, smooth as butter traits, but the push-pull Torii has speed, hit, dynamics and "life" more like live music being performed right in front of you to my ears. I too used to be a drummer and I value percussive snap and that visceral feeling of "air being moved". For me the push-pull Torii just sounds more "real". There are many that will disagree with me - and that's OK - remember that "preference" and "perception" thing.
The SET amps... are more euphonic. Enjoyable at times for some and preferred all the time for others. However, I value the more lively sound of push-pull Decware amps - to each his own. To be honest, I have seriously considered a pair of Decware SET mono's for when I'm in the mood for that type of sound and music that lends itself to that type of amplification. With the sale going on - now may be the time!!
I can tell you, with a high degree of certainty, that you will never run out of power with the Decware Torii and the AN drivers. The Ferrite models are more efficient/sensitive than the Alnico's. Either one gets more than plenty loud with a Torii in a box or mounted in an OB.
The Alnico's are noticeably smoother sounding than the Ferrites overall. With the Ferrites mounted in a box, I really couldn't be happy with them long term. They were just too "forward" and "hot" for my tastes. I never was able to tune/damp them to my satisfaction in a box. But they "calm down" significantly when mounted in an open baffle. There I enjoy them quite a bit.
The Alnico's, on the other hand, mounted in the big 5.6 cu.ft. reflex box recommended by CommonSenseAudio, are very nice. I've never tried to measure them scientifically, but I have a good hunch, they have a 50-60hz hump when tuned per Dicks' recommendation. Whatever the technical reason, they reproduce nearly all music I've ever played through them, driven by my Torii, in a most musical, natural, tonally saturated and juicy manner, that draws you into the music and makes you just want to sit and listen for hours.
One time I actually put one 15 Ferrite in one OB baffle and the 12" Alnico in the other OB baffle. Right out of the gate, you will notice that the Ferrite is significantly louder/more sensitive. When you hear the two side by side like this, even adjusting for volume differences, the Alnico driver sounds "lifeless" compared to the Ferrite. However, when you use the two Alnico's together and listen to them normally, they sound very good in the OB's as well as the reflex box. Truth be known, perhaps the Ferrites are a bit unnaturally "hyped up". Though used in an OB, I find them quite to my liking as do most of the phile's who have passed thru my listening room. As long as they are driven by my Torii or another Decware amp.
On the Decware Torii. I have listened to it on Tekton Lore S', a couple of Omega's, some Gallo's, Avantgarde Duo's... and several others. I have a friend who sold his BAT mono's after hearing my Torii drive his Avantgarde's. Yes.. the Decware amps are right at home in this league.
You have probably seen a lot of discussion about the Wild Burro Betsy driver as used in the Caintuck Audio Betsy baffles. I have a pair of those too. Yep.. the Torii sounds wonderful on them also. However, the Betsy's are too small to light up my large listening room. But in a normal sized room... Betsy baffles may be all a person would desire.
I actually have a rather rare version of the Betsy drivers, know as the "Betsy W.O.W." - Betsy without whizzer. These paired to a high-passed Dayton Audio AMT Pro tweeter do it for me in a big way. Much more so, than regular Betsy's by themselves.
I also picked up a pair of Lii Audio F15's last fall. These are "impressive" drivers. I heard them for long periods of time at last years Zenfest. They are significantly different than the AN drivers I have. I am in fact, right at this moment, building some mounting plates to put these drivers in my Trio baffles in place of the AN 15" Ferrites. I have a hunch, I'm going to like these a lot. If you did not already have the AN 10's, I'd steer you toward the Lii's I think.
On 10 inch full-rangers; Also, last fall at the Decware Zenfest, I listened to the Lii Audio Crystal 10's in the Lii cabinets at great length and driven by several of the Decware amps. I can say this, with confidence, that the Lii Audio Crystal 10's, in Lii's cabinet, have the "most" and "best" upper frequencies of any full range, crossover-less single driver I've ever heard. They were about as airy, open and refined as the best dome tweeters in existence. All other full-rangers sound "coarse" above 6khz or so by comparison.
I could see a future project of Lii Audio Crystal 10's high passed with a cap and augmented on the bottom by my four Augie's. Who knows? This quest never ends as far as I can tell....
Since I discovered crossover-less full-rangers, Decware and subsequently boxless, open baffle speakers to mount the full-rangers in, I have been more "content" than I ever have in over 40 years of chasing the audio holy grail.
My only complaint with full-rangers is dispersion in the upper frequencies. And the larger the driver, the worse this is. The 12" and 15" drivers have that "head in a vice" perfect spot you need to be in for best imaging. They actually sound better, the farther away from them you get. I guess the sound has more time to disperse and blend the farther away you are. Mounting them in an OB, definitely helps "open up" the sound as opposed to mounted in a box, but this aspect still drives me nuts. But I like everything else they do!
What I have experienced by adding the AMT tweeter to the Betsy W.O.W.'s is a vast expansion of air and the "space" that the sound seems to emanate from. I am quite smitten by this characteristic.
I'm already working on my next configuration in my head. As soon as I get the Lii F15's into my OB's and have some time to live with them for awhile, I can see me trying to incorporate the AMT tweeter with the F15's. Perhaps mounted right in front of the F15's. A semi-coaxialish type of mounting, if I can find a way to make it work. There may be sensitivity issues too large to overcome between the drivers - it's just an idea that popped into my head.
I have another set of empty, nice black lacquered reflex cabinets that used to be Definitive Technology BP-20's. I can't let these go to waste! I need to come up with some drivers for these. Maybe some Mark Audio Alpair's or something like that. I'm sure I'll think of something... so many ideas - so little time!
In summary... I don't think you can go wrong with a Decware amp. It comes down to what you, personally like the best. The reason my first Decware amp was a Rachael... was from Steve's recommendation. I got it a little prematurely before I had my first DIY Audio Nirvana project done. And judged it paired with some "well known" big name manufacturers speakers. In retrospect, I wish I hadn't jumped the gun. And I wish I still had the Rachael (SE34I). I think this is kind of the Decware "go to" amp. Perhaps you should try to find a way to audition one of these with your AN's.
Enjoy the Music...