I had a ProAc D38 and ran it with Cary CAD-805AE amps, which are a 50W single ended triode amp. The combination sounded wonderful, but it really depends on the kind of presentation you are after. With the Cary's, the midrange and top end were liquid, airy, and utterly magical. The bottom end left a bit to be desired, and the whole combination seemed to run out of wind fairly quickly when asked to play back a large orchestral piece.
I then tried running it with a pair of Cary CAD-211AE amps (110W push-pull triodes). This combo gives a more muscular and beefy bottom end, but you lose the magical top end of the SET's. You also get more of a sense of effortlessness, as if the dynamics are not constrained by the amp.
I borrowed a 150W Rowland Class A/B amp, which gave a bottom end as good as the CAD-211AE, but midrange and top were not as detailed as either Cary. For a SS amp it was very sweet sounding, not harsh at all.
Just for fun, the D38 has been run with my old Pioneer A400 integrated (70W SS A/B) and it sounded awful. Too bright, harsh, lean on the midrange, and surprisingly lean on the bass.
Your D38 is revealing enough to show deficiencies in upstream amplification. I never did find an amp that I was completely happy with, ideally I would want an amp that combined the bottom end of the Rowland but the top end of the Cary SET. But as always - that is me, and this is based on my preferences in sound and my choice in music! YMMV.