Originally Posted by derbigpr /img/forum/go_quote.gif
I just wanna report that my findings as well are similar to yours. I've tried various amps and receivers and found they all had excellent headphone outputs. At the end I picked the Onkyo A-5VL (~400$) integrated amp with a DAC that has a great sounding headphones output, with loads of power, in fact far more than any headphone amp I've ever tried. Runs DT880's 600ohm with EASE, its very controlled and punchy, and above 60% of volume, its way to loud to listen to, so it's got a lot of headroom. It also sounds great with HD650's, which aren't really that power hungry in comparison, and low impedance Ultrasone HFI-2400's sound great as well.
As far as noise goes, there's none whatsoever on DT880's or HD650's, even at maximum volume, its completely silent. With HFI-2400's there is some barely audible hum when turning the knob to the last 10% or so, but that's very low hum, barely audible, and with such low impedance headphones, either my ear drums or drivers would be blown out way before I could turn the knob that far while music is playing, because it gets too loud to bare even for a second before the knob is turned to 50%.
As for the DAC inside, its a dual (one for each channel) Burr Brown 24/192, second chip from top of the line, the one with 118db SNR, like in Asus D2X card. So a bit weaker than in Asus ST, but I honestly hear no difference whatsoever between using the Asus as a DAC, or just using the built in DAC. Those differences in specs on paper are way above what is audible, its at least as good sounding DAC unit as the Asus ST.
But as a whole unit there is no comparison. Comparing the Asus ST's headphone out and Onkyo's headphone out while using built in DAC, there's no doubt Onkyo wins on pretty much every area. Soundstage is wider, sound is overall somehow bigger, its more punchy, more liquid, more smooth. Just a nicer listening experience.
I also have to say that I've compared it to Asus Xonar Essence One, Teac UD-H01 and Cambridge Audio Dacmagic+ directly, in store, and I had the Essence One at home for a while. Asus and CA are twice the price, and Teac is about 50% more than Onkyo, and Onkyo was at least as good if not better in terms of sound quality than all of them, and in terms of power, it obliterates them all. If we were to put all three units together, they still would not have the power the Onkyo has, and they're all dedicated head amp/dac combos that cost much more.
As you've said, and I agree, it makes my Asus ST redundant, as well as my head amps, and makes the idea of buying a separate headphone amp or DAC seem totally pointless, especially after hearing most of the <1000$ offerings. Also, as far as looks and build quality goes, there's no competition with standalone head amps or DAC's. This unit looks business, it weighs 23 pounds, it feels solid like a rock, all the knobs have a high quality solid mechanical, but at the same time smooth feel, there's a remote control, volume pot is motorized, and lets not forget a great speaker amp part as well. Possible bi-wiring and plenty of power for my Kef Q300 speakers, which are pretty big and pretty power hungry.
