Pani, what wire are you using to bi-wire the Tannoys?
I have used quite a few. When I was using Naim amplification I used the NAC A5. Now I am using wavac valve amplification so I have tried speaker cables from Harmonix, ASI Liveline, Chord. The thing is, with Tannoy, while biwiring makes everything sound very airy and open, the feeling intimacy and tight coherence is lost in the process. The speakers disappear more readily when biwired, but that feels more like a special effect because music becomes too distant. It is just my observation with Tannoys. As, I said before, with ATC biwire is a must.