If you already like the A19, then you should go for it. ... Alhough, whether it is enough to get the Tannoys going depends on your preferred listening levels, and size of room. Have you considered and listened to the discontinued A28 and A38? They have more power on tap than the A19 and may suit you better especially if you like listening at higher volumes. Just a thought.
Then there is Myryad. iirc, a former Arcam tech designer went over to this company with the effect that Myryad amps do take after Arcam's fine neutrality. I like the Z140, its a communicative 50-watter. Its successor is the Z142, which offers a future option of biamping with the companion Z162 power amp for better control of the Tannoys. Worth considering.
cheerSS