Well, my new uDAC-2 arrived in the mail today!
It certainly is small, and from a design point of view, it is quite nice. I had limited time tonight to try it out, so these are my first impressions. I briefly tried it out with my netbook and with my laptop, and I used my HD-600s and my Ety ER-4Ps without the S converter cable. I did not connect it to my main rig, and I made no attempt to optimize anything. The computers were running on battery, and I also hooked up an external DVD/CD burner to play a few tracks from a CD. First, the good news. The uDAC-2 had plenty of power to drive my Senns nicely with some room to spare. I had too little time to make any kind of comparison, but I did like what I heard. And, I could not hear any of the hum/noise/beep discussed above through the Senns. As it was a long day, I almost fell asleep listening to Ella Fitzgerald sing, and that is always a good sign. Now, for the not so good news - the noise is clearly present in my Etys. It was not volume dependent, and is clearly there when no music was playing.
Its way too early for me to make any kind of decision about this, as most gear I have encountered over the years, high end as well as budget, seems to have some "issue" that you need to make peace with if you are going to keep it, use it, and not drive yourself crazy. The big test for me will be when I hook things up to my main rig later this weekend, as that was one of the primary reasons that I chose the uDAC-2 - it has RCA outs. Having it present in the Etys is not a big issue for me as when the uDAC-2 is not hooked up to my main rig, it will probably be powering my Senns or a pair of desktop monitors/speakers. The Etys have mostly been relegated to portable use and for airplane travel. I like them, but they are very clinical, as I was reminded again tonight. I look to my Senns when I want a pleasant musical experience, and the uDAC-2 seemed to play very well with them on first impression. I could not detect the sound in my Etys when music was playing, but I would not want to hear it for any extended period of time when the music stopped. The uDAC-2 with my Etys reminds me a lot of my telephone headset at work. I can hear it when it is powered up, but not in use. Its noise floor is not offensive by any means, but, I do turn the unit off if I am not going to be using it for any length of time, as I can easily tell the difference of when it is powered up or not.
Schedule permitting, I hope to do more listening this weekend, and will report back accordingly.
--Ken