I thought the list price for a D400 was just under £10k now, plus there was a recent discount offer of 15% off. So you should have paid no more than £8500? There was also some talk of a reduced price for the upgrade for those who bought Expert range amplifiers this year, I am not 100% sure on this last point though.
1000 Pro - KEF Blade - iFi Zen Stream - Mutec REF10 - MC3+USB - Pro-Ject Signature 12