Solid states more accurate than tubes?

I thought the question was which is more accurate in reproducing not creating. The artist   and associatiated technicians creates, we simply try to reproduce what they created. In order to be faithful to that creation then accuracy is paramount. If I don't care for the creation then I can color it with distortion or tone controls that's my decision. But to answer the original question which is more accurate solid state or tubes in reproducing I would say solid state. 

we are painting a watercolour here, not fastidiously documenting an actual event".

That might be what you’re doing but the original question was not how can I paint a watercolor but which device REPRODUCES the original more ACCURATE. If you have 1% THD then you’re not reproducing the original but coloring it with distortion and that’s fine if that’s your goal but it’s not answering the OP question of Accuracy it's just offering your preference.

Depends on the tube amp some have very good measurements very linear and some SS amps measure pretty bad. That said it seems most people who like tubes do like the coloration tubes offer. There is no right or wrong but if accurate and neutral are your goals SS is easier to find that with. 

Probably the most accurate amp you can get is the Benchmark AHB2. They would work with your speakers.

I assume by true fidelity you mean high fidelity? High fidelity in audio means reproduction of sound without distortion and color that remains true to the original. In order to achieve that you need very accurate measuring equipment. The biggest obstacle now is speakers and room.