That'll be an interesting experiment, for sure.
I've sat down with both amps and both the 007mk1s and 9s and while I agree with Spritzer that the BH beats out the "stock" 500V HV, they both sound amazing. To these ears the differences between them are pretty small. Its nowhere near the difference you hear when you go from a production level Stax amp to either the BH or HV.
You really can't go wrong either way.