So in light of my impressions of the DFB in my previous post above, and using easy to drive headphones like the NAD VISO HP50, Brainwavz HM5, and ATH M50s, would I benefit from "upgrading" to the DFR? Is it worth another $120 CAD for my setup? I'm thinking of ordering one from amazon anyway and just A/Bing them, but I'd prefer not to pay return shipping costs only to keep my DFB. I could save that money and perhaps save-up for a separate dedicated desktop unit for home use later on.
I've read most or all the reviews on both here and elsewhere, and there is a great deal of disagreement about the sound signature of the DFR and comparisons between the DFR and DFB. The only general conclusions I can seem to make out from reviews are that the DFR enhances highs more than the DFB and creates even better soundstage/separation, and it is better for driving higher impedance headphones.
Mixed opinions:
-Some consider the DFR red to be more neutral than the DFB, while others suggest it is even darker/warmer despite more enhanced highs.
-Others suggest the sound of the DFR is almost glassy and too sharp, while the DFB is more neutral/warm.
-Several suggest the DFB has more/better bass response, while others suggest that the bass of the DFR is more extended and much clearer.
I don't have the time or inclination to go back through all the posts I've read here to cite those that support one point or another; suffice it to say, there are large disagreements, but the general consensus is that the DFR is a better product overall. I think most disagreements and incongruities can be chalked up to differences in headphones, sources, and preference. Someone noted that the DFR doesn't colour much, but instead enhances what is being projected - i.e. if your source and phones tend to be bright/dark, the sound will be brighter/darker. That makes sense to me, though I'm sure the DFR adds its own flavour.
Volume issues - many people have incorrectly suggested that the DFB is "louder" than the DFR even on the PC (on smartphones this might be true). According to audioquest themselves, this perception is due to volume stepping. At lower volumes, the DFB is louder simply because the analogue volume steps are larger. The DFR has a more fined tuned digital volume tuner that has smaller steps but becomes much "louder" at the higher end of the range than the black.