Want ot go for valves amp

Anyone please give me some opinion about this integate amp that i have listed below, Which one do you think the best valve integate.
I am just about to change my system into valve. The pre/power I have got at the moment is Avi s2000p and alchemist forsetti signature power. and My speaker is Zingali overture 2s(91db).

- unison research simply 4
- audio note soro se
- tube technology unisis
- Unison research 845(the most expensive one).

I know the 845 might be the best one but i would like to know some opinion about others as well like simply 4 or unisis. Or should i go for valve pre/power but this will costs me much more expensive. I may get the new power first then following by the preamp later.


Thanks