Budget Tube Amp (newbie)

Upscale Audio has some nice used tube integrateds.
https://www.upscaleaudio.com/collections/amplifiers-specials
Ditto The Music Room
https://tmraudio.com/components/integrated-amplifiers/
Also US Audio Mart - Tube Integrateds
https://www.usaudiomart.com/search.php?keywords=&cat_id=55&price_min=&price_max=&typ...

I have a PrimaLuna PL5 power amp which drives my 84db/W Spicas to almost as loud as I ever want
I also have a pair of tubes4hifi M-125. Their amp kits are great value and lovely sounding amps, but I wish I'd built them myself.

HOWEVER, we I you, I would first investigate upgrading the crossover caps in the Advents.

Old iron IS better than new iron.

Old iron is frequently cheaper than new iron.

Quad II sounds much better than Citation II

I never thought so, but I don’t like Welch’s & ethanol either. IMO, the CII is more coherent from the low mids on down while the QII were somewhat confused in the systems in which I heard them.

In tube sound, the warmth you like is supplied most by a tube preamp.

No it’s not. In all cases, the entire system contributes to the final sound. A nice tube preamp is not going to help a system with a Zippo 250 SS amp and EarBleed speakers wired with HFXtreme cables. A tube amp may be more/less intolerant of cable/LS.

Systems are built with ’recipes’, all little of this, all little of that to achieve a good balance and just like pudding is all in the eating, amps are all in the hearing.

Hogwash!
Old iron is no better than new iron. A good design is a good design.
A great 60W KT-88 amp is a Citation II, but they are pricy.
Lots of old vintage stuff is in need of a complete rebuild, not just capacitors.
Tube rolling is silly. Get something that sounds well and be done with it.

Just enjoy the music!

We definitely agree on the Islay.
Best I ever had was a 30 year old Ardbeg distilled in 1972.