Keep in mind the Schiit Vali is almost released as well! I'd start with it first, granted it won't be as nice as the Valhalla but the two apprently share a simmilar sound. Ofc the Vali is half as much and offers a little less power I'd think.
non the less the Vali would be a good place to start. $120 is a dang good bargin. ANd I Used and very much enjoyed my DT 990 off a Indeed G3 Hybrid Tube! That said those $100 hybrids aren't to bad, the Vali how ever should be a top choice in that price range. As most $100ish Hybrids are made by some Chinnese Company that has little well feed back honestly... Schiit on the other hand is American Made and they have a good record of great products and customer service. Combine there Rep with the a $100 Hybrid Tube, and I think it's going to be a real winner