Help me choosing an Integrated Amp

Hello everyone,
long time reader, first post here.
Sorry if my english is not perfect, it’s not my mother language.

Long story:

I have an electrostatic headphone system right now, because I didn’t have the necessary space to have a dedicated room for speakers, I think that the most important aspect in sound quality is room acoustics, so why spend money if I can’t have optimum acoustics? That’s why I have a headphone system right now.
But, story changes, I bought a flat last week, and will do reforms to have a listening room (6 meters x 4 meters x 2,5 meters).
My current setup is (besides modded Stax SR-007A and KGSSHV Carbon CC amplifier):

- Metrum Pavane DAC
- Custom 0db PC, Asus RT-AC88U router & MCRU linear PSU for router.
- Full Ansuz X Cable loom and Mainz X-TC.
- Furutech FWS (R) Schuko Outlet.
- Sonore MicroRendu & Sonore Signature PSU (with SR fuses)

My speakers will be Strauss Elektroakustik SE MOD 901, they’re not very well known but they’re awesome, transient response is lighting fast, almost like my Stax headphones, plus they’re super coherent, seamless. I fell in love with the speakers.
Room acoustics will be done by Strauss himself, so the last link is an integrated amplifier (for budget and price/performance reasons).
The speakers are not very sensitive, they’re rated at 85db and recommended power is 20 to 160w at 8ohm.

Due to budget reasons, I will try to buy second hand or ex-demo, so not possible to audition the amplifiers.
I don’t like tubes, for me, the ideal amp should be pure class A (if possible), dual mono, fully balanced with no negative feedback (if possible). Ideal "sound signature" would be balanced, very natural without glare, huge soundstage and details presented in a natural manner, I don’t like hyped top end, the speakers are VERY neutral and accurate, so they will expose negative qualities of the amp like a magnifying glass.
This is the list:

- Audio GD Master 10 (Class A/B, 250w at 8ohm)
- Gryphon Atilla (Class A/B, 100w at 8ohm)
- Accuphase E-600 (Class A, 30w at 8ohm)
- Pass Labs INT-30A (Class A, 30w at 8ohm)
- Electrocompaniet ECI 5 MK2 (Class A or A/B???, 120w at 8ohm)
- Ayre AX-5 Twenty (Class A/B, 125w at 8ohm)
- Constellation Inspiration Integrated 1.0 (Class A/B, 100w at 8ohm)

I like to listen music between 70-85db (not too loud) and the room will be 24 square meters, is a 30w pure class A amp enought for the speakers or should I buy a more powerful class A/B?
Which amp is better?