@ContractorHei, while I've never heard a DV 336, I have a BH Crack and have used my friends Valhalla2 a few times along with my Lyr2 and Ember, the BH Crack is the best pairing with the HD-650 in this price range IMO. Just remember that you will/should change the stock tubes and this will add to the cost. My favorite tubes for the Crack are TS-5998 for the power tube and Telefunken 12AU7 for the driver, note that these will add about $150-250 to the price of the Crack.
If you have other headphones then I would seriously look at the Ember, it is much more flexible since you can change the output resistance to match almost any headphone out there and the 12XXX series tubes are not the most pricy at this time or if you feel like pushing it there are adapters to go to dual tubes and other tube families.
The Valhalla2 is the most neutral sounding between the Crack, Ember and Lyr2, it can be dry sounding to some but the dynamics are quite good IMO. I haven't done much tube rolling with it, only rolled the drivers so its basic characteristic didn't change much to me, seems like tube rolling has less of an effect on the Valhala2 than on the other amps where tube rolling has a larger effect on the sound characteristics of the amp.
DACs that I use: UD-301, Bimby, Uber and 4490 Modi.