Low power amps don’t sound better they just have less power.
This statement is problematic. Most traditional amps of A or AB design tend to sound better in lower powered embodiments. In the case of all transformer coupled tube amps its because the output transformer has wider bandwidth; in solid state amps its often because less output devices are in parallel and so the circuit has less complexity.
I agree that the speakers are a good thing to keep. A surprisingly good little integrated amp is the old Dynaco SCA-35, but it would have to be refurbished (replaced filter capacitors in the power supplies and any parts not to spec; you'll need to find someone competent at this sort of thing) to really strut its stuff. It has the best output transformers Dynaco ever made, and they made some pretty good transformers. Its a 15-Watt/channel amp using EL84s. You might look at other EL84 amps available too, such as the Leben CS300.
Since the room is not that large and the listening tends to be light jazz, an SET could work quite well too. I would also consider some of Nelson Pass' lower powered amps, like some of his First Watt stuff, if tubes seem too daunting. I would also consider a powered subwoofer to help out in the bass department; if it is not operating above 60-70Hz it will not draw attention to itself no matter where it is in the room (and you might have to move it around a bit until you find a spot where its output is nicely audible at the listening position).
Above all- this is supposed to be fun. Don't sweat it, and be willing to audition the components that interest you in your room. BTW, any tube amp will need at least 1/2 hour warmup to really be taken seriously.