Most musical, enjoyable affordable amplifier

First Watt F7, XA60.8’s, Accustic Arts Power ES, NAD m22 - none perfect, but all pretty musical amplifiers I currently own.  Two that I currently own but a little disappointed with from a musicality standpoint: Leben CS300 is a little too flabby (although headphone section is satisfying), Krell Evolution (a bit too analytical and thin, but has some wow factor areas as well).

That being said, I think the DAC section is the starting point of the conversation.  Preamps are fun to compare and contrast as well.  

I bought a modern single ended tube "boutique" guitar amp (I'd owned old Fender amps, some of which were single ended) and liked it a lot, and it got me wondering what single ended tube hifi would sound like after many SS amps over decades, although at the time I was enjoying a push-pull tube power amp in the rig. I read about Dennis Had and watched an interview with him on Youtube that I liked, and a slightly used Firebottle amp showed up on Ebay. After a year or so I'm still smitten, and while using it with efficient speakers and a tube preamp it simply works for me as it sounds astonishingly good. Seems to be a keeper.

One of my favorite amps was the little PSE Studio IV. Compared to just about any other amp near it's price, whether driving my Vandi 2Cs or Quads, it was like pulling back a veil and just hearing the music...Jim

The most enjoyable listening , out of scores of amps, tube and ss, I have ever enjoyed, is the humble little Dynaco ST-35 with Mullard el-84's, and a Pass First Watt F6 clone  built from Pass article ,and DIY Audio web site.
Class A does it for me.

On digital ,it is the Lumin D-1,that Foes Tidal, MQA,Roon, with the excellent Mojo audio seperate 12v power supply 12lbs  still early 6am .
Gato Audio Integrated class D but stacked with technologies
I HAVE THE 400s 40wpc,800 In to 4ohms .Architecture looks great also.
Natural warmth ,and iron grip .over 20 design upgrades in the New S model 
Not cheap but will compete no problem with any competing brands.and the digital Section is very well balanced .

The Lafayette was my first decent fidelity receiver I owned with a dual turntable 
Klipsch Heresy speakers .back in the 70s for a 17 year old kid it was special 
Compared to most in my neighbor hood . After owning a Audio store in Europe until 07 .j have learned Synergy means more then just buying class- A recommended components ,and my quest now is buying the best sounding 
For far less money . My latest is the Gato Audio from Denmark wonderfully 
Built sounds exceptionally good and looks great this New S series even the built in dac is a BB 1794 , also  Monitor Audio hit their new Studio out of the park,their monitor speaker with engineered matching stand a must,all drivers taken from their flagship pl500 Platinum series,
Little R&D left except cabinet & Xover  for under $2k just buy a good sub and you have a $10k plus setup. No joke beats speakers 5x this .sold outaround the World, 4-6 week back order.
Tidal digital player with Mojo power supply A Giant killer. Last but not least 
Verastarr audio cables latest no frill line without the fancy weave and a bit less
In sound damping ,a fantastic line of cables ,and Excellent new Power cord 
No more then a middle priced kimber or Cardas for example but with better resolution. These are all very good buys for $$ spent.  Happy listening !!

I will keep my Lafayette KT-550 amp.  Sweetest amp I own or have heard.

Happy Listening.

We all have a bespoke preference (actually a bias for "X" number of reasons .....) as to what actually stirs our drink, that is impossible to engender on the next dude.

For example, some dudes drive FORDs, some drive CHEVYs, and yet some drive JAGs, LAMBOs or BENTLEYS as their own strong opinion of a superior ride contender among a vast sea of previously culled-out pretenders ( note: pretenders ONLY to them .... ) ; thus the anecdotal and heavily biased influence factor .