You should check out Skylab's review of the Audeze Edition Isabelina HPA wherein he compares the Isabellina DAC section to the Havana... http://www.head-fi.org/t/572939/review-red-wine-audio-audeze-edition-balanced-headphone-amplifier-dac-combo
"This decision was furthered by the fact that the [Isabellina] AE's DAC was much better than the MHDT. I like the MHDT quite a bit, actually, and think it sounds very good, especially for the money. But the MHDT is much less neutral than the AE. I like the Havana’s “sound”, but it has a sound, for sure, regardless of tube rolling. It isn’t neutral. And that was the primary trait that impressed me about the AE’s DAC – it was extremely neutral and stunningly transparent."
leesure, thank you for the link!