First class - F5 / F5 turbo or F6 for tannoy 15 speakers

Unfortunately, I have never heard a Pass amp, but the XA25 sure got exemplary reviews.  Realizing you are in UK, not sure if you could score on a gently used demo from Reno HIFI.  They seem to hold their value.

Aaah lots to digest I've sent you dm.....

The arden legacy are 93db and a pretty steady 8ohm so get loud pretty easily but clear... 15inch driver so a lot of air moves

He also regularly builds standard! F5 f6 amps and the aleph J - pics of turbo build if that gives any indication

He is  Joeh283 https://www.ebay.co.uk/usr/joeh283/all-follows

 ebay.co.uk

Someone has built one already and sells off his older build projects - the speakers are quite warm already so transparency and sound stage is more important to me

Details this 2 x 50Watt into 8 ohms Class A amplifier.
This is the nelson pass F5 turbo pure design

'the design takes minimalist approach to attain low distortion and exceptional musical performance
It really is the best of both tube and solid state world.

Distortion @ 1 watt .001% to .005% @ 1 KHz
Input Impedance 101 Kohm
Damping Factor 60
Output power stereo 8 ohms 50 watts @ 1% THD, 1KHz
Voltage Gain 15.3 dB
Maximum unclipped output +/-20 Volts
Maximum output current 10 amps
Frequency response - .0 dB @ DC, -3 dB @ ~ 1 megaHertz
Noise ~60 uV unweighted, 20-20 KHz
EMI filtering
Speaker protection'

But will have a look at others you mention.