Jp1208, I just ordered a pair of the ref 9s with the extended bass option. Last night I had an opportunity to compare a Dartzeel NHB-108 with a pair of Ref. 9s. It was set up in my system, playing through a pair of Von Schweikert Audio VR-4jrs and I'll tell you, the Nuforce amps were not embarrassed by the Dartzeel by any stretch. The Nuforce amps are the real deal IMO. The Dartzeel definitely had a more refined, analog-like sound, but the Nuforce were pretty darn close. There were 3 of us listening, and I think we all came to the same conclusion. With some tweaking and system-tuning, I would bet you can get 80-90% of the performance of the Dartzeels with the ref 9s. From that listening session, I decided to order a pair. The pair I heard did not have the extended bass option, so it will be interesting to hear the differences between the two versions (extended bass vs standard).