Originally Posted by Capunk
D2000 please. thank you.
I have just now started burning in the headphone amp section, since it had less than 1 hour on headphones with it, being that I have only been using the speaker amp section for driving Stax headphones. The burn-in is because I listened to the Nuforce tonight and compared it against my Travagans Red with AD743, Apogee mini-DAC headphone out, and Woo WA6 - using my APS V2 re-cabled Denon D2000.
All the amps were fed from my Marantz CD5001 via coax out with a Synergistic Research digital coax cable into Apogee mini-DAC. From the Apogee to WA6 via XLR to RCA tranformer and Neutrik XLR and anticables IC's. The Nuforce was fed from the 1/8" line-out of the Apogee via Jenna Labs mini-mini cryo cable with Canare F12 plugs. Travagans Red was fed from the 1/8" line/pre-amp out of the Nuforce with an ALO Jenna Labs cryo interconnect, so I could have all three running at the same time with the same source. (If the Travagans was worse than the NuForce, being fed by the Nuforce pre-amp out, the plan was to go direct to the Travagans in place of the Woo WA6).
With the Nuforce, what I found using the D2000 was a nice and enjoyable sounding headphone amp section, but with slightly recessed highs that were missing a little sparkle, and with slightly forward mids. Bass was slightly behind the other amps as well, but not rolled off - it was just not quite as punchy as the other amps. It was not extra-airy sounding at all, as previously reported, rather it seemed slightly dark. The Nuforce Icon headphone-out was somewhat below these other amps, sounding more like a Meier HeadSix portable when used with the D2000 - meaning very nice but not #1 (certainly worth the money considering all the features and the excellent speaker amp section, being only $20-30 more than Headsix after shipping). The Travagans Green sounds like a Red, but only has USB input so I didn't test it. I have the Firestone Cute Beyond packed up to ship to another reviewer, so I didn't test it this time, but having compared it to the Travagans I have to say my guess is that it beats the unburned-in Nuforce as well.
I will wait to see how the Nuforce sounds with 100 hours on the headphone section, so I will report back this weekend. Almost every amp I have burned-in has opened up with 200-300 hours on it (except the Predator needed 400-600 minimum to really open up, and usually 1000 or more to stop changing). The Travagans took 250-300 hours for the bass to fully appear with the stock LM4562 opamp. During the burn-in I will try it with the HD600, Edition 9 and RS-1 too. Then if not raised to a higher level of performance, I will give it another 100 hours of burn-in, and so forth.