Does anyone know how I could get an RK-60 to 5U4 adapter?

Where did you purchase your Lindemann DAC?

Great news on USB DAC functionality. +1 on fixing the other issues listed above by CJG888!

Awesome! I bet you love it!

I agree that am ping the DX50 does improve sound quality and bass response. I use a Headstage Arrow 4G which is the size and shape of a credit card and has great features such as adjustable treble, bass and crossovers. Check it out.

Vemon, the battery will drain somewhat quicker with increasing volume output through the headphone jack. When using a portable amp, you would connect through the line out and the amp would control the volume.

No experience with that amp but DX50 and HD600 together are great, and if you use a quality amp things will likely improve, I think there's an upper level of what you can get out of this level of equipment. The next level requires a serious headphone amp, DAC, and better headphones. That's what...

Just search their website. Find a couple of candidates that have the features you like and then read reviews on those. I had the same need for an in line DAC as well as wanted Bluetooth, but I went with the DX50 for sound quality and usability and I'm really delighted. I use an old Itouch in my...

Cowon. You seek Cowon .

I primarily use more portable gear with the DX50 but it's terrific with my HD600s. Definitely improves further with my Headstage Arrow credit card-like amp, but the DX can definitely drive HD600 with pretty good results.

Correct.

The waiting is the hardest part. I ordered my Startus many weeks ago with expected delivery in June.This will certainly be the most high end component I own or have ever owned and I'm interested in your opinion on the stock tubes. I surmise that upgrading my HD600 to HD800 as well as upgrading...

Very easy to have USB attached to the Ibasso DX50 with a cable. A little more battery drain but works well. I can also attached my portable 2 TB Drive of Grateful Dead! Rock on!

Thanks everyone for the DAC rec's, especially Bigfatpaulie for the epic rant!