Affordable integrated pure class A?

Get a used Sugden integrated if you really want affordable class A. They have been in business a long time and service what they have sold. Very reliable.

Not a lot of power so they need fairly efficient speakers.

Generally, a class A/B all tube amp sounds far better than most SS amps for comparable money, and one with Pentode/Triode switching will generally sound even better than that, and there are a lot of options for those including relatively inexpensive Primalunas to more pricey Rogers High Fidelity amps...and many in between. Not sure if anybody makes a tube single ended integrated amp, but although generally requiring efficient speakers, that could be even better sounding than most other options.

@wolf_garcia 

Line Magnetic and some others make integrated SET amps, but not in the OP’s price range.

need to look no further than Accuphase, pure class A integrated is about as good as it gets.

Second the Sudden A21SE recommendation.  I own that amp myself.  It is immediate in reproduction.... I mean really quick.  Everything else seems slow off the mark and a bit sloppy.  Midrange is sweet and bass is tight but not thunderous or really deep.  Do not shy from the 30 watts Class A.  It will drive most anything and scary loud.

It does not possess the sweetness of really good tubes, so don't believe that comparison.  I run Manley tube gear and it will not compete there, but then it did not cost 14K.....duh.  Terrific piece.