Your needs and equipment sound very familiar.
I am very familiar with the Parasound A21.
I prefer the A21 for reasons I can't fully explain and its been my champion amp since 2016. I had cycled thru a few different combinations of solid state & tube models .
For my current budget, nothing has beaten it yet. As for SS preamps , I have tried the Parasound PHP 850(old!), P3(ditto), and New Classic 2100 pre-amps with varying levels of success in achieving the "low volume / full frequency, deep sound field" that I have always sought for my own ears. During this time I experimented with the half step tube buffer options
(IFi Tube2 and Jolida SSX )
and eventually settled on keeping them in the signal chain full time. They run between my source (Cary DMS 500 DAC/Streamer) and pre. Both buffers added some of that additional space mentioned earlier but were not enough alone to fully engage my ears. At my level of investment-SS preamps simply lacked these same factors to fully fill in the space of my listening room.But then the day arrived of trying my first tube preamp. The Vincent SA-1 finally ended the journey. The combination of the A21 and the Vincent is as close to what I can afford and be able to live with on a day to day basis. The only thing that comes close to that is the Vincent SV-237 integrated (again a SS/Tube hybrid) in my second system.
I did do some limited experimentation with tube amps. No matter the pre -the Prima Luna Prologue, which was a beautiful and well built amp , just lacked the low volume oomph on the low end. And for those of us in the desert Southwest, it also added an unnecessary amount of warmth to my already toasty room. And whenever a tube amp was in the equation it always-even at low volume- transmitted extra noise and hiss thru my ZU OMEN towers.
Now this works for me and is not perfect! I realize a larger investment may change the game. As I listen mostly at low levels and I enthusiastically utilize loudness and tone controls, I do run into some issues when my volume occasionally goes past 8:00 O Clock! ( This is the portion of the program when somebody will pipe in on a impedance mismatch or a need to throttle down the Parasound's gain for more useful scale from my pre). Anyway hope that helps for perspective.